They broke the plug-in API years ago and haven't bothered to fix the new one meaning I'm stuck with ugly tabs on the top even when I use Tree Style Tabs. Scrapbook extension hasn't worked for years etc.
Today, the main reason I use it isn't technical superiority but stubbornness, idealism and rhe fact that the alternatives are just as bad. I.e. despite all the progress on speed etc nothing makes up for breaking the single reason why they were the work horse of browsers: the extensions ecosystem combined with cross platform and good baseline performance.
FWIW: Mozilla can get money from me today - if they promise to use it to fix Firefox.
They wont. Quite on the contrary they are quite clear that donation money goes to other projects. I understand this has something to do with Mozilla being a non profit and browsers development not being a thing in their charter, but sooner rather than later I hope they'll realize that providing a good, free browser is maybe the biggest thing they can do to secure an open web ecosystem.
I already donate money directly to other projects, so I am not interested in that.
I will be signing up for the VPN thing however once it becomes available and if I know the profits goes to Firefox (irony over irony is if I'll need to use a VPN to sign up for the VPN I want :-P)