TLDW: MegaLag found code and rules in the Honey extension that modifies behaviour specifically to make discovery of non-compliance with affiliate programs and affiliate poaching harder for testers. This behaviour has been in place since 2017 at least.
There are also various browser extensions to show you an image from the middle of the video instead of a thumbnail. I personally prefer that.
The hate for the thumbnail for this video I don’t get, but there is some REALLY egregious thumbnails on YouTube sometimes