Use DeArrow! It not only removes clickbait thumbnails, but replaces them with community-sourced ones, allowing one to choose a thumbnail frame from the video and have it better put up for a vote, and it does the same thing for the video's title! It's made by the same guy who made Sponsorblock.

I use Mr. Beastify for that bc I like to suffer, but having the Beast everywhere makes it warp back to around not being annoying anymore for some reason and sometimes he shows up under a red triangle or something like that :3

*.youtube.com 127.0.0.1