Well, this is a worrying new development

[evensgrey]

It appears YouTube has instituted a new way of concealing videos.  This video by Sargon on his The Thinkery channel

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did not appear in subscriber feeds (I know it didn't appear in mine), and doesn't appear in the video list of the channel page either, and has no thumbnail, despite not being in any identifiable limited state.  I checked, and you can like/dislike, comment, and it even came up with an ad when I viewed it.

Sargon thinks this is a sort of shadowban feature like Twitter uses against people it just wants to suppress without admitting to it.  You might want to check your video lists to see if anything you've posted is missing in this way.