Updated to mysql 8 on a new server instance, and broke the whole website. But this guy did too, and was kind enough to write a blog post about it. It worked! Things are up and running once again.
I had the same problem as this user here and sure enough, it was Pi-hole. I love Pi-hole but you really do have to be careful when adding a whole bunch of lists. It’s easy to break stuff. I’m more careful now. 🙂