Context or it is a trivia number
Browse traffic and search traffic click differently. A suggested video next to a huge creator can show a lower CTR and still be a gift. A video shown only to subscribers should not have a terrible CTR. If it does, the thumbnail and title are not telling your own audience what this is.
When CTR falls as impressions rise, that is often the video meeting colder people. Judge it with watch time. A high CTR and a fast exit means the package overpromised.