Don't know if this will help assuage your fears: https://www.techradar.com/news/mullvads-no-log-policy-proven-after-police-raid
I've used Mullvad for years, and from what I know, they store almost nothing -- only your randomly generated account number. If you are paying using an anonymous method that's even less to go on.
Y'all know what I do fer a livin'
Reminded me of Quint from Jaws!