Do you mean Vaultwarden? AFAICS they do not "settle" on it, but they do argue that it is much lighter in almost every respect. And since it is Bitwarden compatible the comparison is valid.

I don't know which one I mean, because OP never says which SaaS password manager they switch to, they simply say they switch to a proprietary SaaS password manager:

For group A I’m going with a SaaS password manager that offers proper vault sharing, integrates with the tools clients actually use (SSO, browser extensions on corporate machines, audit logs), and takes the hosting burden off my plate. The platform is proprietary, which I would normally not be thrilled about, but given that the scope of this group is client work only, I’m accepting the trade-off.