I know YouTube will rate thumbnails and tell you how the thumbnail is doing. I believe they also uploaded a feature where you can upload multiple and it will attempt to change them to see which works best. I see this a lot with Minecraft YouTubers (mostly Grian). It seems to be less trying to trick previous viewers and more so getting the highest rating in the YouTube panel. I think it is partially bs, as there are times I’ll scroll past a video not wanting to watch it at the exact moment and it seems like YouTube takes that as being a bad thumbnail.
I love everything about wanderer, just wish that you could look at trails on a full-screened map on mobile. Currently pulling up the trail will provide a small map inside the webpage for you to see the trail, which on desktop works great, but mobile it feels like the map should be the more important aspect (similar to apps like osm, all trails and gaiagps). Because of this I am mostly using it as a database to then download the trail and open it in osm.