Youtube is not playing nice with oEmbed discovery and is captcha/blocking some of my servers from getting oEmbed links. So, some instances were not presenting the video preview card for YouTube.
As a temporary solution I will be applying this fix https://github.com/tootsuite/mastodon/pull/12229
A restart of the services is required and a ~10 second downtime is to be expected in the next hour.
BTW: the missing YouTube video preview cards that are older than 15 days will automatically be fetched. So, if you have posts with missing preview cards from YouTube videos just wait some days and they will start to show up.
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