That different FOSS client stores your data on their company’s server. It’s an important factor, IMO.
Dude, how is bitwarden hosting your own, locally encrypted (in FOSS client) password database any different than using keypass and syncing it however you want?
I don’t even use Bitwarden myself, I’m using keepass too, but this attitude is … weird?
I find risk slightly bigger when you encrypt your private data with the product of the company and store that encrypted data on servers of the same company.
Why: because if they have some backdoor now or plans to introduce it in future, they have all the time in the world to apply that backdoor to your data. Without you knowing it.
Bitwarden client is FOSS same as Keepass, though. Why aren’t you afraid of Keepass having backdoor by “insert whatever big corporation sponsoring FOSS” giving said companies free access to your passwords you happily store in their clouds?