Thanks for the post; I'm also having major issues with battery drain when using Mullvad.
But what exactly do you mean by “Turns out the ad-blocking DNS for Mullvad I was using was causing the issue. I turned it off and just used the ‘Block Ads’ auto DNS setting, and bam. Fixed.”
Do you mean the ad-blocking options in Mullvad itself that you disabled? What do you mean by “auto DNS settings”?
That setting doesn’t exist in Mullvad.