I use KeepassDX on family mobiles with Syncthing for copies between laptop and phones. What would i gain moving to Vaultwarden, knowing that i would never open my network to the outside world? It would be easier to manage for sure, as im having to setup phones and laotops myself in the family and worry that they do silly things like turn off syncthing. But what about offline access to passwords? Does Bitwarden mobile client keep a local copy of database until it can sync?
tl;dr: yes, credentials are cached locally. https://github.com/dani-garcia/vaultwarden/discussions/4676
The major downside to the single file storage used by Keepass is that it’s easy to accidentally create a conflict between files on different devices if they’re not synced immediately. Conflicting files have to be merged manually or data might be lost. I’ve run into this several times with Keepass + Nextcloud. In comparison, a central master database with local cache can resolve conflicts between individual records.