Clickbait remover uses YouTube’s auto generated ones, which while are seemingly random, are not. They use some algorithm to target faces in exaggerated expressions.
DeArrow uses actually random ones (and then a user can submit specific timestamps if there is a better one). It’s noticeable better on many channels imo
YouTube Clickbait-Buster has a feature where you can see all the images from the hovering preview from the seekbar. A more refined version of that could be interesting to look into in the future maybe.
Wait, the default thumbnails are no longer just chosen from three points in the video based on percentage? Now they use algorithms to generate a suitable thumbnail too?