No screen blanking/locking after youtube watching

For some reason unknown to me xautolock started to behave erroneously after I watch youtube videos. Interestingly enough this happens only when using Chromium-based browsers (Chromium, Vivaldi, Brave). Firefox does not affect the locker. If I don’t open youtube, then the locker acts as usual, I mean, it works. If I surf thru links with embedded videos but don’t watch them the locker works. So, apparently, the culprit is youtube.
Here is my i3 config line for locker:

exec --no-startup-id xautolock -time 10 -corners +00- -locker blurlock

I tried to add the following to the config line

xset dpms force standby

so, that the line looked like this:

exec --no-startup-id xautolock -time 10 -corners +00- -locker blurlock && xset dpms force standby

but to no avail. However, when I run these commands in my terminal

blurlock &

or

blurlock && xset dpms force standby &

everything runs alright, i.e. the screen blurres and blanks and locks.
After some googling I’ve read this short discussion
and tried to kill all processes in one way or another connected with youtube running in browsers, but it didn’t help.
So, any help will be appreciated. Or should I use
xdg-screensaver ?

That is likely a youtube service worker which keeps running after you have closed the browser.

There is a setting in chrome based browsers which specifically disables the browser’s ability to keep running in the background. (icon in taskbar?)

chrome://settings/system

Yes, it is there. I have disabled this option. Forgot to mention it.

p.s. Tried several lockers, still no positive result.