Maybe try it out on standard Firefox as a quick test? While annoying, this would help validate that the issue is with the librewolf changes to standard Firefox.
Also note that I also use both proton mail and drive from librewolf. Even today. If it’s a general issue with this setup, it hasn’t hit my machine (yet)
I use proton vpn and Firefox Focus on iOS. I’m not sure which of them is doing the heavy lifting, but I rarely see ads on my phone.