diff --git a/.eslintrc.js b/.eslintrc.js
index 7452532984..67999a3a2c 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -49,14 +49,7 @@ module.exports = {
     'import/no-unresolved': [
       ERROR,
       {
-        ignore: [
-          '^@theme',
-          '^@docusaurus',
-          '^@generated',
-          '^@site',
-          'unist',
-          'mdast',
-        ],
+        ignore: ['^@theme', '^@docusaurus', '^@generated', '^@site'],
       },
     ],
     'import/extensions': OFF,
@@ -149,6 +142,7 @@ module.exports = {
         allowSingleExtends: true,
       },
     ],
+    '@typescript-eslint/method-signature-style': ERROR,
     'no-restricted-imports': [
       ERROR,
       {
diff --git a/packages/docusaurus-theme-classic/src/index.ts b/packages/docusaurus-theme-classic/src/index.ts
index f54af080ba..2b90541672 100644
--- a/packages/docusaurus-theme-classic/src/index.ts
+++ b/packages/docusaurus-theme-classic/src/index.ts
@@ -5,12 +5,12 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import {DocusaurusContext, Plugin} from '@docusaurus/types';
+import {DocusaurusContext, Plugin, PostCssOptions} from '@docusaurus/types';
 import type {ThemeConfig} from '@docusaurus/theme-common';
 import {getTranslationFiles, translateThemeConfig} from './translations';
 import path from 'path';
 import {createRequire} from 'module';
-import type {AcceptedPlugin, Plugin as PostCssPlugin} from 'postcss';
+import type {Plugin as PostCssPlugin} from 'postcss';
 import rtlcss from 'rtlcss';
 import {readDefaultCodeTranslationMessages} from '@docusaurus/theme-translations';
 
@@ -132,7 +132,12 @@ export default function docusaurusThemeClassic(
     },
 
     getTranslationFiles: async () => getTranslationFiles({themeConfig}),
-    translateThemeConfig,
+
+    translateThemeConfig: (params) =>
+      translateThemeConfig({
+        themeConfig: params.themeConfig as ThemeConfig,
+        translationFiles: params.translationFiles,
+      }),
 
     getDefaultCodeTranslationMessages() {
       return readDefaultCodeTranslationMessages({
@@ -178,7 +183,7 @@ export default function docusaurusThemeClassic(
       };
     },
 
-    configurePostCss(postCssOptions: {plugins: AcceptedPlugin[]}) {
+    configurePostCss(postCssOptions: PostCssOptions) {
       if (direction === 'rtl') {
         const resolvedInfimaFile = require.resolve(getInfimaCSSFile(direction));
         const plugin: PostCssPlugin = {
diff --git a/packages/docusaurus-theme-classic/src/translations.ts b/packages/docusaurus-theme-classic/src/translations.ts
index 2b7a3ab6ab..be96e3b6c1 100644
--- a/packages/docusaurus-theme-classic/src/translations.ts
+++ b/packages/docusaurus-theme-classic/src/translations.ts
@@ -151,6 +151,8 @@ export function translateThemeConfig({
   themeConfig,
   translationFiles,
 }: {
+  // Why partial? To make TS correctly figure out the contravariance in parameter.
+  // In practice it's always normalized
   themeConfig: ThemeConfig;
   translationFiles: TranslationFile[];
 }): ThemeConfig {
diff --git a/packages/docusaurus-theme-search-algolia/src/theme-search-algolia.d.ts b/packages/docusaurus-theme-search-algolia/src/theme-search-algolia.d.ts
index e93073b41f..005a694670 100644
--- a/packages/docusaurus-theme-search-algolia/src/theme-search-algolia.d.ts
+++ b/packages/docusaurus-theme-search-algolia/src/theme-search-algolia.d.ts
@@ -12,10 +12,8 @@ declare module '@docusaurus/theme-search-algolia' {
 declare module '@theme/hooks/useSearchQuery' {
   export interface SearchQuery {
     searchQuery: string;
-
-    setSearchQuery(newSearchQuery: string): void;
-
-    generateSearchPageLink(targetSearchQuery: string): string;
+    setSearchQuery: (newSearchQuery: string) => void;
+    generateSearchPageLink: (targetSearchQuery: string) => string;
   }
 
   export default function useSearchQuery(): SearchQuery;
diff --git a/packages/docusaurus-theme-translations/update.js b/packages/docusaurus-theme-translations/update.js
index 74b5b20866..3422918f56 100644
--- a/packages/docusaurus-theme-translations/update.js
+++ b/packages/docusaurus-theme-translations/update.js
@@ -235,6 +235,8 @@ ${logKeys(untranslatedKeys)}`),
 }
 
 async function updateCodeTranslations() {
+  // Order is important. The log messages must be in the same order as execution
+  // eslint-disable-next-line no-restricted-syntax
   for (const theme of Themes) {
     const {baseFile, localesFiles} = await getCodeTranslationFiles(theme.name);
     logSection(`Will update base file for ${theme.name}`);
@@ -259,6 +261,7 @@ async function updateCodeTranslations() {
         );
       }
     } else {
+      // eslint-disable-next-line no-restricted-syntax
       for (const localeFile of localesFiles) {
         logSection(
           `Will update ${path.basename(
diff --git a/packages/docusaurus-theme-translations/update.test.js b/packages/docusaurus-theme-translations/update.test.js
index 5f786dca76..f8c8626aae 100644
--- a/packages/docusaurus-theme-translations/update.test.js
+++ b/packages/docusaurus-theme-translations/update.test.js
@@ -21,7 +21,7 @@ describe('theme-translations package', () => {
       await fs
         .readdirSync(baseMessagesDirPath)
         .reduce(async (messages, baseMessagesFile) => {
-          messages = {
+          const newMessages = {
             ...(await messages),
             ...JSON.parse(
               await fs.readFile(
@@ -29,7 +29,7 @@ describe('theme-translations package', () => {
               ),
             ),
           };
-          return messages;
+          return newMessages;
         }, {}),
       (_, key) => !key.endsWith('___DESCRIPTION'),
     );
diff --git a/packages/docusaurus-types/src/index.d.ts b/packages/docusaurus-types/src/index.d.ts
index 36101f75b2..a9be044725 100644
--- a/packages/docusaurus-types/src/index.d.ts
+++ b/packages/docusaurus-types/src/index.d.ts
@@ -220,10 +220,10 @@ export interface Props extends LoadContext, InjectedHtmlTags {
 }
 
 export interface PluginContentLoadedActions {
-  addRoute(config: RouteConfig): void;
+  addRoute: (config: RouteConfig) => void;
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  createData(name: string, data: any): Promise<string>;
-  setGlobalData<T = unknown>(data: T): void;
+  createData: (name: string, data: any) => Promise<string>;
+  setGlobalData: <T = unknown>(data: T) => void;
 }
 
 export type AllContent = Record<
@@ -239,32 +239,32 @@ export type PostCssOptions = Record<string, unknown> & {plugins: unknown[]};
 
 export interface Plugin<Content = unknown> {
   name: string;
-  loadContent?(): Promise<Content>;
-  contentLoaded?({
+  loadContent?: () => Promise<Content>;
+  contentLoaded?: ({
     content,
     actions,
   }: {
     content: Content; // the content loaded by this plugin instance
     allContent: AllContent; // content loaded by ALL the plugins
     actions: PluginContentLoadedActions;
-  }): Promise<void>;
-  routesLoaded?(routes: RouteConfig[]): void; // TODO remove soon, deprecated (alpha-60)
-  postBuild?(props: Props): void;
-  postStart?(props: Props): void;
+  }) => Promise<void>;
+  routesLoaded?: (routes: RouteConfig[]) => void; // TODO remove soon, deprecated (alpha-60)
+  postBuild?: (props: Props) => void;
+  postStart?: (props: Props) => void;
   // TODO refactor the configureWebpack API surface: use an object instead of multiple params (requires breaking change)
-  configureWebpack?(
+  configureWebpack?: (
     config: Configuration,
     isServer: boolean,
     utils: ConfigureWebpackUtils,
     content: Content,
-  ): Configuration & {mergeStrategy?: ConfigureWebpackFnMergeStrategy};
-  configurePostCss?(options: PostCssOptions): PostCssOptions;
-  getThemePath?(): string;
-  getTypeScriptThemePath?(): string;
-  getPathsToWatch?(): string[];
-  getClientModules?(): string[];
-  extendCli?(cli: Command): void;
-  injectHtmlTags?({content}: {content: Content}): {
+  ) => Configuration & {mergeStrategy?: ConfigureWebpackFnMergeStrategy};
+  configurePostCss?: (options: PostCssOptions) => PostCssOptions;
+  getThemePath?: () => string;
+  getTypeScriptThemePath?: () => string;
+  getPathsToWatch?: () => string[];
+  getClientModules?: () => string[];
+  extendCli?: (cli: Command) => void;
+  injectHtmlTags?: ({content}: {content: Content}) => {
     headTags?: HtmlTags;
     preBodyTags?: HtmlTags;
     postBodyTags?: HtmlTags;
@@ -272,31 +272,31 @@ export interface Plugin<Content = unknown> {
   // TODO before/afterDevServer implementation
 
   // translations
-  getTranslationFiles?({
+  getTranslationFiles?: ({
     content,
   }: {
     content: Content;
-  }): Promise<TranslationFiles>;
-  getDefaultCodeTranslationMessages?(): Promise<
+  }) => Promise<TranslationFiles>;
+  getDefaultCodeTranslationMessages?: () => Promise<
     Record<
       string, // id
       string // message
     >
   >;
-  translateContent?({
+  translateContent?: ({
     content,
     translationFiles,
   }: {
     content: Content; // the content loaded by this plugin instance
     translationFiles: TranslationFiles;
-  }): Content;
-  translateThemeConfig?({
+  }) => Content;
+  translateThemeConfig?: ({
     themeConfig,
     translationFiles,
   }: {
     themeConfig: ThemeConfig;
     translationFiles: TranslationFiles;
-  }): ThemeConfig;
+  }) => ThemeConfig;
 }
 
 export type InitializedPlugin<Content = unknown> = Plugin<Content> & {
@@ -310,9 +310,9 @@ export type LoadedPlugin<Content = unknown> = InitializedPlugin<Content> & {
 
 export type PluginModule = {
   <T, X>(context: LoadContext, options: T): Plugin<X>;
-  validateOptions?<T>(data: OptionValidationContext<T>): T;
-  validateThemeConfig?<T>(data: ThemeConfigValidationContext<T>): T;
-  getSwizzleComponentList?(): string[];
+  validateOptions?: <T>(data: OptionValidationContext<T>) => T;
+  validateThemeConfig?: <T>(data: ThemeConfigValidationContext<T>) => T;
+  getSwizzleComponentList?: () => string[];
 };
 
 export type ImportedPluginModule = PluginModule & {