GPU frequency, temp and usage going wild on Linux

Compositing on or off, the behavior is the same.
Gpu frequency, temp and usage are randomly going wild, even launching the fans on what seems to be a totally random basis, while idling on the desktop.
The card’s a RTX 2070.
I’m actually idling at 55°c versus 45°c on Windows. On which the GPU freq is lower and much more stable.

Welcome to the club: