I can’t see the numbers on your images on my phone, but I will answer in the generic sense.
When outside of a flight in the MSFS menus, there is not much for the CPU to do, so the GPU will crank away and give as many frames per second as it can, unless limited by some setting.
Inside of a flight, MSFS will be processing physics, aircraft avionics and systems, talking over the network, loading scenery, processing weather, multiplayer or AI traffic, ATC, etc. In the course of doing this, if your CPU becomes a bottleneck, your fps may decrease, while your GPU waits for the CPU to catch up. You may want to turn on developer mode and see if you’re CPU- or GPU-bound.
If you want the GPU to consume less power while not flying, you can go to the Options menu, and go to Experimental, and enable low-power mode. That will remove the 3D background from the menus and result in a significant load reduction on your GPU.