Your VPN can see EVERYTHING about you: IPs, timestamps, servers, session lengths, and more. What devices you have, what time you wake up, what sites you go to, what you're doing, all your unencrypted stuff, the job you have. It knows more about you than you know about yourself.
Even more... they see all your dns, what you request, what you download, even if encrypted. SNI requests are not, which means every site you visit they see. Do they log? Who knows? Can they deploy anti-log software when they're audited? Yes. Can that change after? Also yes.