This is one of the rare cases where I believe security through obscurity applies.

What is the most ripe attack target: the password hosting service with millions of user credentials, or literally some random IP address using syncthing that could be sending literally anything that you don’t know is passwords or porn.

Companies like Bitwarden and 1Password and LastPass are doomed to have failures, just like any major corporation. They are too big with too much attack surface, and clearly advertise that they have stuff worth stealing.

Me? My KeePass vault is synced via Syncthing with no relay data, so it only ever exists on my phone and desktop, and is encrypted with what is today functionally unbreakable encryption. Today at least (RIP when quantum chips get good).

And my data is a blade of grass in a field. Sure there is a narrow chance someone snooping on my entire geographic area and stealing packets like the FBI could grab some packets in transmission. But they show nothing, and mean nothing. And the FBI has easier ways to get our data anyways.

Point is, I’d rather take my odds as a heavily encrypted file syncs between singular devices like a drop of water in the ocean, versus putting all my diamonds in Joe’s Diamond Emporium and just hoping no one decides to steal MY diamonds when it (inevitably) gets robbed.

Agree on the versioning issue. In fact I mentioned that the issue is convenience here. It is also data corruption, but you probably are aware of that if you setup something like this. Manually merging changes is extremely annoying and eventually you end up forgetting it to do it, and you will discover it when you need to login sometime in the future (I used keepass for years in the past, this was constantly an issue for me). With any natively sync’d application this is not a problem at all. Hence +1 for convenience to bitwarden.

However KeePassXC’s sync feature does sync the vault.

How does it work though? From this I see you need to store the database in a cloud storage basically.

For mobile I just give syncthing full permission to run in the background and have never had issues with the syncing on the folders I designate.

I use this method for my notes (logseq). Never had synchronization problem, but a lot of battery drain if I let syncthing running in the background.

Nothing else passes through it unless you opt into using relaying in case you have NAT issues.

I guess this can be very common or even always the case for people using some ISPs. In general though, you are right. There is of course still the overall risk of compromise/CVEs etc. that can lead to your (encrypted) data being sent elsewhere, but if all your devices can establish direct connections between each other, your (encrypted) data is less exposed than using a fixed server.

If you are paranoid, the software is open source and you can host your own relays privately,

This would also defeat basically all the advantages of using keepass (and family) vs bitwarden. You would still have your data in an external server, you still need to manage a service (comparable to vaultwarden), and you don’t get all the extra benefits on bitwarden (like multi-user support etc.).

To be honest I don’t personally think that the disclosure of a password manager encrypted data is a big deal. As long as a proper password is used, and modern ciphers are used, even offline decryption is not going to be feasible, especially for the kind of people going after my passwords. Besides, for most people the risk of their client device(s) being compromised and their vault being accessible (encrypted) is in my opinion way higher than -say- Bitwarden cloud being compromised (the managed one). This means that for me there are no serious reasons to use something like keepass (anymore) and lose all the convenience that bitwarden gives. However, risk perception is personal ultimately.