As Linus (and other YouTubers for that matter) have said, awful thumbnails and clickbaity titles work.
And when YouTube is a side gig you can refuse to do it on principle, but when you need to pay 100 folks (in case of LMG) - I don't think it's much of a choice.
Let's face it, we're fricking old. The demographic of YouTube is getting younger and younger and the young 'uns engage more in cringey reaction face of thumbnails. It's not a coincidence that YouTube/Google is going hard on anything that might not be "kid friendly". They de-monitised lots of historical YouTube channels for being "age inappropriate". Unfortunately, there are no alternative to YouTube. I love Nebula, but sometimes you'd just want videos and channela where you can just turn your mind off.
Doesn't surprise me, Mr Beast recently posted that A/B testing showed that the classic open-mouth YouTuber Face thumbnails don't perform as well as the creepy dead smile does. Linus thinks Mr Beast is a YouTube Algorithm God (and should be president of the US!), so I'm sure he jumped on that.