Nice! Have you heard of this web extension?
I use it on all my pcs. It seems to be in a similar spirit to your solution 
– kuba-orlik 2021-05-09 20:22 UTC
Interesting, thanks! I used to use LeechBlock, which (for some reason) scaled poorly (in terms of RAM consumption) with the number of tabs open, so I had to uninstall it. I’ll check this one out, since my solution is definitely a dirty hack and not very convenient!
– mbork 2021-05-10 16:54 UTC