Locked FPS overridden

I've recently bought FSRealistic Pro and ran into the following weird problem:

To safe some power and not generate excessive heat I've limited my 3090 to 40fps with the NVIDIA control panel. The overlay provided by RTSS & Afterburner shows that the FPS in-game is never over that limit.

However, as soon as I start FSRealistic (which gets its own overlay and runs at around 80-120 fps) MSFS is no longer respecting the limit of 40, instead it is getting up to 60fps (on a VRR 120Hz display). Obviously that increases the GPU load by a mile, sometimes even hitting 99% or running into the power limit.

As soon as FSRealistic is closed, the limit is again in force.

Has anyone else seen this, and if yes, what was the solution?

Thanks!