If it were throttling, you would see reduced clock speeds and/or reduced power. However, I’m not seeing any graphs for frequencies and power. Have you checked?
If you don’t know what tool to use you could check LACT: https://github.com/ilya-zlobintsev/LACT
I find this to be great and am particularly comforted by the following:
Can my SteamOS Compatibility test results be worse than Deck Verified?
No. SteamOS Compatibility results will all be the same or higher than Steam Deck Verified results.