It’s the scratchpad script where you copy/paste into the about:config console. I just did it for the new v.115 release. I’ve done it previously but I don’t have any set schedule. I guess 1x every six months (2x/year) seems sufficient but I wanted to see what others do.
Mullvad is great for people who don’t want to tweak their browser settings very much. But lots of us see the tweaking as a feature, not a bug. I customize the heck out of my browser and appreciate that FF allows for the customization.