The team behind the very popular and fantastic open source video capture software OBS Studio have done a Steam release. For Linux users though, you should just stick to Flatpak from Flathub.
With the Steam release it's only supported for Windows and macOS, and their official Steam FAQ post mentions they have "no concrete plans for providing a Linux build on Steam". Why though? They said they can just re-use existing builds for other platforms but for Linux it would need another additional build done. However, they also said they will "look into the feasibility of providing such a version" but they're quite busy.
A shame perhaps but the good news is that the version available on Flathub is officially supported by the OBS team and works across pretty much any Linux distribution. In fact, it's the exact package I use for all video recording and livestreams so I can definitely recommend it anyway.
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