Syncing is a huge part, UX is another. I was using KeePass on my desktop for several years before I met my wife, and having her use it was a complete failure. She did not like the workflow. Having to open another another tool, login, search for the correct site, and copy/paste the password was too much friction. And that was when things worked.

Syncing was an utter disaster. Inevitably something would cause syncs to be delayed, and then there would be a conflict and one of our changes would be silently lost. We were constantly going to lookup a password we entered, and finding it was not there anymore, at which point I would have to dig through sync conflict backup files and manually reenter the passwords that were lost, or go through the password reset flow for the sites. It was a giant mess, and that was just with two desktops and a laptop. I was using btsync at the time but all the issues I encountered apply to any file based synchronization, like syncthing, nextcloud or dropbox. Performing whole database file synchronization is simply not the right approach for password safe.

I eventually switched over to self-hosted BitWarden with the browser plugin and it has been much smoother.