Unlike Samsung Internet and Brave, this extension kept working amid the recent YouTube changes. The extension works for any website. Switching tabs / apps keeps the audio of media playing in the background.

Available on iOS via Safari and Microsoft Edge. Available on Android via Edge, Firefox, Yandex, Kiwi Lemur and other firefox/chromium browser supporting extensions.

https://microsoftedge.microsoft.com/addons/detail/keepbackpl...

https://apps.apple.com/app/keep-back-play/id6755731215

https://addons.mozilla.org/firefox/addon/keep-back-play%40ap...

https://chromewebstore.google.com/detail/keep-back-play/ojhb...