The UI of Opt-in Browser Prompt is entirely in the control of the web browser and the language it's shown is dependent on Operating System's and Web Browser's Preferred Language settings. It cannot be dynamically set/altered. If you're using a translation app that allows users to switch to a different language, the browser prompt won't respond to that change.

However, if you change the Operating System's preferred language to, let's say, French, the browser prompt will be translated properly.

To change your Operating System's language, you can refer to the official guides: