Sure, but at the end of the day even if you don't update your vaultwarden server or you rely on an insecure storage sync system like dropbox, your actual vault is encrypted with a key that only you know. Even if your server is hacked or the kdbx is leaked, your passwords are safe until someone breaks AES.

Contrast that with hosted services, who could very easily attach their own keys to your encryption key (whether now or in the future at the behest of the state) and you'd be none the wiser. E2EE doesn't matter much when the other end is controlled by someone else.

I'm not disagreeing that most people just want something to work without thinking about, and for that reason I'm glad that services like bitwarden and lastpass and protonpass exist. My intent was not FUD, just shining a light on the fact that keeping your passwords secure does not require trusting a company.

And simultaneously less secure because it’s up to you to handle keeping your vault synced between various devices and most people are significantly worse at keeping systems secure than the professionals at the password managers.

It is not less secure.

If the Bitwarden servers are compromised (either by hacking or by being forced to by the government of the country where they are hosted) then code could be run which would allow the attacker to receive your plaintext password and that is used to decrypt your data.

If a user is so horrible at syncing that they accidentally synced their database file to a public Twitter post, it is still protected by AES-256 which can't be broken by a simple subpoena.

In either case, syncthing is pretty simple to use and is the common recommendation for the kind of small personal file sync that you need here. It also adds an additional security layer, on top of the unbreakable AES-256 encryption, to the whole setup.