It's annoying because I contributed UX to this librewolf feature a few years ago (because I really wanted it), its finally landed but I can't use it - it was the blocker to adopting the more strict privsec model that librewolf offers by default (it solves the 'cookie exceptions are a pain to manage' problem. Obviously something to do with my kitchen-sink Firefox profile folder copy, but for now I guess I'll just carry on with cookies persisting and at some point rebuild a fresh librewolf profile if I want to adopt their defaults.
So there's at least that, if this ambigious license stuff (and recent ad company purchases) bothers you, you can probably just copy your profile into Librewolf's profile folder, rename, and have done something about this perceived issue without a major disruption