Youtube channel similar. Total wipeout, no reason given. Complain & they just say you "nothing wrong with your Gmail account" - go figure!

I am sure it would have been hacked. I hadn't touched it for years (& not change the password!).
Saw a video of someone complaining the same, his sole source of income! He was sure he had answered a "helpful" website/app so he was definitely hacked. With inappropriate content. The point is you cannot then remedy the situation by changing the password removing content etc. All of which screams - Youtube vulnerability that can't/won't be plugged.
With Youtube using more adverts all the time, they just can't/won't allocate resources to address the issue.