Bitwarden is now verified on Flathub for Linux
If you would read the post you just linked, you could found the update at the bottom: https://www.phoronix.com/news/Bitwarden-Code-Cleared-Up
Stop spreading FUD, the issue was resolved, they separated correctly the foss and not foss parts of the software.
Not foss part only used on the server side on the cloud version, if you use the self hosted vaultwarden and any official client, everything is still foss, you can build it fron source.
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