I've cancelled my subscription yesterday, conveniently it was about to renew at the end of the week, so I have a few days to migrate from Proton, here's what I'm thinking of, but I'd love to hear what other people are switching to
It seems it hasn’t happened yet. They are still open source for now. I am still using my Vaultwarden with Bitwarden.
It seems it might be going that way though.
If it goes fully closed source then I imagine the fix will be Vaultwarden devs coding some replacement apps.