Prehistory: On the phone (android, xiaomi) of the child, "Google Family Link" is installed with a time limit for using applications (when the screen is on). But the child turns on an audiobook or video and turns on the screen lock - the media plays in the background and the time of using the phone does not increase.
Question: How to block media browser playback with a locked screen?
I did not find a solution in chrome://flag and phone settings (sounds, battery). Turning off the sound in the tabs is also not an option (it's easy to turn it back).
Maybe I missed something and was looking in the wrong place?