I use KeepassXC and synchronize the encrypted database across my devices using my own Nextcloud instance. But even if I used a mainstream cloud provider, that wouldn't matter since the db is encrypted and decrypted locally. Regarding trusting the frontend, in my case I just need to check that KeepassXC itself isn't sending data around. Which I admit I didn't do so far, but in my view the alternative of reusing password is much more likely to get you in trouble compared to the likelihood of KeepassXC sending your data to a tird party without anyone noticing.