PAYDAY 2 came to Linux officially back in 2016 but as of today they've removed support for it, so it will no longer see updates on the Native Linux version.
It does, however, still work quite well with the Windows version via Steam Play Proton on desktop Linux and is Steam Deck Verified against the Windows version in Proton. So while it’s a loss of support for their Native build, it’s still fully playable on Linux.
I have a feeling we’ll be seeing this more and more often as Proton improves