This seems fishy, they are using the old logo. Have you checked their email domain? If that isn't the normal YouTube domain be sure to change your password if you have already logged in through their link.
A lot of people have reported the same problem - playlists deleted even if none of the videos in the list seemed to violate guidelines. One of the respondents in the thread I just linked had reported this problem 2 months ago, but it doesn't look like they have an update. Just in case, you may want to contact YouTube anyway.
PitchforkAssistant on November 9th, 2017 at 14:30 UTC »
How can a playlist violate the community guidelines? Shouldn't the videos in the playlist be taken down instead?
JurdeV on November 9th, 2017 at 14:39 UTC »
This seems fishy, they are using the old logo. Have you checked their email domain? If that isn't the normal YouTube domain be sure to change your password if you have already logged in through their link.
RyanMNg on November 9th, 2017 at 14:52 UTC »
A lot of people have reported the same problem - playlists deleted even if none of the videos in the list seemed to violate guidelines. One of the respondents in the thread I just linked had reported this problem 2 months ago, but it doesn't look like they have an update. Just in case, you may want to contact YouTube anyway.
Edit: YouTube finally responded and confirmed it was a bug, as per /u/livelyraisins's post below.