docs: note that custom args are on your own risk (#28656)

https://github.com/microsoft/playwright/issues/28537

docs/src/api/params.md

@@ -911,8 +911,12 @@ between the same pixel in compared images, between zero (strict) and one (lax),
 ## browser-option-args
 - `args` <[Array]<[string]>>
 
+:::warning
+Use custom browser args at your own risk, as some of them may break Playwright functionality.
+:::
+
 Additional arguments to pass to the browser instance. The list of Chromium flags can be found
-[here](http://peter.sh/experiments/chromium-command-line-switches/).
+[here](https://peter.sh/experiments/chromium-command-line-switches/).
 
 ## browser-option-channel
 - `channel` <[string]>

docs/src/chrome-extensions-js-python.md

@@ -6,7 +6,7 @@ title: "Chrome extensions"
 ## Introduction
 
 :::note
-Extensions only work in Chrome / Chromium launched with a persistent context.
+Extensions only work in Chrome / Chromium launched with a persistent context. Use custom browser args at your own risk, as some of them may break Playwright functionality.
 :::
 
 The following is code for getting a handle to the [background page](https://developer.chrome.com/extensions/background_pages) of a [Manifest v2](https://developer.chrome.com/docs/extensions/mv2/) extension whose source is located in `./my-extension`:
@@ -214,6 +214,10 @@ def test_popup_page(page: Page, extension_id: str) -> None:
 
 ## Headless mode
 
+:::danger
+`headless=new` mode is not officially supported by Playwright and might result in unexpected behavior.
+:::
+
 By default, Chrome's headless mode in Playwright does not support Chrome extensions. To overcome this limitation, you can run Chrome's persistent context with a new headless mode by using the following code:
 
 ```js title="fixtures.ts"

docs/src/test-api/class-testoptions.md

@@ -347,6 +347,10 @@ export default defineConfig({
 
 Options used to launch the browser, as passed to [`method: BrowserType.launch`]. Specific options [`property: TestOptions.headless`] and [`property: TestOptions.channel`] take priority over this.
 
+:::warning
+Use custom browser args at your own risk, as some of them may break Playwright functionality.
+:::
+
 **Usage**
 
 ```js title="playwright.config.ts"

packages/playwright-core/types/types.d.ts

@@ -13020,8 +13020,10 @@ export interface BrowserType<Unused = {}> {
     acceptDownloads?: boolean;
 
     /**
+     * **NOTE** Use custom browser args at your own risk, as some of them may break Playwright functionality.
+     *
      * Additional arguments to pass to the browser instance. The list of Chromium flags can be found
-     * [here](http://peter.sh/experiments/chromium-command-line-switches/).
+     * [here](https://peter.sh/experiments/chromium-command-line-switches/).
      */
     args?: Array<string>;
 
@@ -13458,8 +13460,10 @@ export interface BrowserType<Unused = {}> {
    */
   launchServer(options?: {
     /**
+     * **NOTE** Use custom browser args at your own risk, as some of them may break Playwright functionality.
+     *
      * Additional arguments to pass to the browser instance. The list of Chromium flags can be found
-     * [here](http://peter.sh/experiments/chromium-command-line-switches/).
+     * [here](https://peter.sh/experiments/chromium-command-line-switches/).
      */
     args?: Array<string>;
 
@@ -14500,8 +14504,10 @@ export interface AndroidDevice {
     acceptDownloads?: boolean;
 
     /**
+     * **NOTE** Use custom browser args at your own risk, as some of them may break Playwright functionality.
+     *
      * Additional arguments to pass to the browser instance. The list of Chromium flags can be found
-     * [here](http://peter.sh/experiments/chromium-command-line-switches/).
+     * [here](https://peter.sh/experiments/chromium-command-line-switches/).
      */
     args?: Array<string>;
 
@@ -20041,8 +20047,10 @@ interface AccessibilitySnapshotOptions {
 
 export interface LaunchOptions {
   /**
+   * **NOTE** Use custom browser args at your own risk, as some of them may break Playwright functionality.
+   *
    * Additional arguments to pass to the browser instance. The list of Chromium flags can be found
-   * [here](http://peter.sh/experiments/chromium-command-line-switches/).
+   * [here](https://peter.sh/experiments/chromium-command-line-switches/).
    */
   args?: Array<string>;
 

packages/playwright/types/test.d.ts

@@ -3809,6 +3809,8 @@ export interface PlaywrightWorkerOptions {
    * [testOptions.channel](https://playwright.dev/docs/api/class-testoptions#test-options-channel) take priority over
    * this.
    *
+   * **NOTE** Use custom browser args at your own risk, as some of them may break Playwright functionality.
+   *
    * **Usage**
    *
    * ```js