I've seen streaming services spoil an episode with just the thumbnail. I can't remember what show's twist was ruined for me, but I'm pretty sure it was Netflix.

Netflix also has a really annoying habit of re-ordering seasons. For some bizarre reason shows like bake off are listed with the most recently added series first. For some shows that might not be a huge problem but in the first episode of one series they actually recap the winners of all previous series, spoiling several years of programing for unwary netflix viewers.