I had some performance problems. Suddenly, steam deck lost about 60% of its performance in games. My troubleshooting didn't help. After that, I contacted steam support. We were talking for about a week, but nothing helped, so they agreed to send me a replacement.
I have to say… The fresh vent smells even better than I remember.
Definitely not a thermal issue, the temps barely climbed and the fan never ramped up. It seemed like a TDP lock of 1W or so but only on the CPU as the GPU core would happily boost up still.