Comment # 6 on bug 1187195 from Takashi Iwai

Actually, a system without a GPU driver *might* consume higher power because it
keeps the chip active without runtime PM.  And nouveau as fallback doesn't work
always well.

But you confirmed that it's WiFi, and this can be easier to handle, I assume.
Could you check whether the similar behavior is seen on the older TW kernels
(without Nvidia graphics)?  You can find the old kernel packages in my OBS
repos, e.g. home:tiwai:kernel:5.11, home:tiwai:kernel:5.11, etc.
  http://download.opensuse.org/repositories/home:/tiwai:/kernel:/5.11/standard/

It'd be helpful if you can figure out whether a kernel regression or not (and
which kernel starts showing the bad performance).