I had a shock a few days ago when my YT channel got a first 'strike' and had a created playlist removed. I appealed unsuccessfully. My channel was effectively 'frozen' for a week.
"We have reviewed your appeal for the following: Playlist: P23 - South Asian vloggers We have reviewed your content carefully and confirmed that it violates our child safety policy. We know that this is probably disappointing news but it's our job to make sure that YouTube is a safe place for all. How this impacts your content We won't be putting your content back up on YouTube. If your appeal was for a strike, the strike will remain on your channel."
I was surprised because (a) the playlist in question was 'unlisted', also (b) that the content was from other people's channels. YT would not say which vid(s) had brought this about. I wonder why YT don't remove the offending vid(s) from those channels, which would of course automatically remove them from mine? That seems fairer to me. As a precaution I have temporarily reset a lot of my playlists to 'private' while I have time to review the contents, which may take some months as I am busy in other spheres.
Looking on Reddit, several other people have reported similar problems. This is the only explanation of the rules that I've found: https://support.google.com/youtube/answer/9713446?h I.e. there are some videos which might be ok by themselves, but putting them in a playlist is bad, particularly if it has a dodgy title.