[jaen]

Changing orientation affects which parts of the display processor are used. In general, the low power states on GPUs are very capricious.

eg. from personal experience, on older Nvidia cards (1080 Ti), just adding +1Hz to the refresh rate (or using a slightly higher resolution, or 10-bit color, or no DSC etc. etc.) caused it to never enter low power mode, changing power consumption permanently from 10W -> 50W.

AMD GPUs on even the most modern Linux kernels don't enter low power states properly. If you do change the power profile to do it more often, browsers become a laggy mess.