Youtube thumbnails cards not rendered properly

This is series possibly (un)related observations regarding behaviour of thumbnail preview cards in toots with Youtube links.

Normal toot with a link to Youtube shall look like this (https://qoto.org/@FailForward/105541689329961055):

From about January 16th 2021, toots with links to not have a Youtube preview card like this: https://qoto.org/@FailForward/105566110715456396

Or have an empty one like this: https://qoto.org/@FailForward/105605039151550298