In response to ASMR Duck. Just passing along the message. Please donate here to help... https://givealittle.co.nz/cause/alber... Any AdSense money I get off this I plan on donating.
To listen while using other apps, switch the player to Picture-in-Picture (PiP) during playback — it keeps playing in a small floating window (the screen stays on).
To listen with the screen fully off, in-browser playback stops by YouTube's design. Open the video in the YouTube app to keep listening where background playback is supported (e.g. with YouTube Premium).
Open in YouTube app