Gregory's Server
What I heard when I first noticed it showing up was, because of the way a post to the fediverse propagates to multiple servers, YouTube was seeing multiple hits for the same URL and preview at once and it looked like a DDOS attack.
Then instances had to create intermediary servers with generic previews to prevent whatever lockouts were triggered by the appearance of a DDOS attack.
@Chancerubbage @renchap @rmondello
It sounds like a good solution would be to propane YT meta data with the post. Other servers can retire the data with some randomized timeout to prevent the appearance of ddos.
Alternately a federated system could have a random server propagate refreshed data retained for a randomized interval. Then
some other server would “win” the job.