Your VPN provider would either host their own DNS Resolver or “outsource” that to an already existing provider. DNS Resolving basically translates “google.com” to “8.8.8.8” (or Google’s IP Address). Whoever resolves your DNS queries knows what website you are trying to access making them one more entity in the loop on your browsing activities. This is why is is important to use privacy-respecting DNS providers such as Quad9, NextDNS, and those listed on the PG site. For more information, I was able to find What is a DNS Resolver & How to Set it Up | NInjaOne on a quick search.
Hope this clarifies it a bit.
- Haris