No, I didn't. If I understand flatpaks correctly, they need quite big downloads (as well as installed size on disk) of runtimes which can amount to some GBs only for installing an application which is not more that some MBs. But of course next time you install an application which runs on the same runtime the download size is "normal". So I have been avoiding them but if I decide to install Bitwarden's after all, I'll surely let you know how it works.
I wanted to try the appimage since it won't install on the system and runs like a portable app. Bitwarden has a .deb as well, I might give that a try.