#Edit: This has been resolved now.
For those of you who've been using the Steam Deck variant of Bazzite on desktops/HTPCs with AMD GPUs - beware that currently there's a bug affecting (some?) users, where the GPU's TDP is capped to just 15W!
You can check your settings by running a tool like LACT (ujust install-lact):
As you can see, LACT shows the current limit is 15W, but it can actually go upto 280W on my card.
A bug report for this was opened last year, but it was closed as fixed, but at least one other user (besides me) has been experiencing it - so check your wattage, you might be affected too!
At the moment there are no actual fixes - but you can try the workaround posted in the original bug report. Also, using tools like LACT or corectrl isn't a fix unfortunately, because as soon as you go into game mode (or reboot), the limit resets back to 15W. I'm currently troubleshooting this with a couple of the developers, and hopefully we may get to bottom of this soon.
As for the performance impact - here's a screenshot of Last Epoch running at a glorious 4 FPS, thanks to the caps:
Not sure, there aren't many reports so it's hard to say. I know at least the ROG Ally version has its own service which sets the TDP so it's probably not affected.
As for the Steam Deck, if you're running this on an actual deck it's not really a concern because 15W is the Deck's default TDP. And Bazzite-Deck is Steam-Deck-first distro, so you're still really better off using Bazzite.
Also, to clarify, this is a case of Steam (Gamescope) itself changing the TDP, so it's not a bug introduced by their devs.