I have a laptop with both a dGPU and iGPU. when gaming i see the nvidia dGPU in use but the Activity Monitor remains "grey". If i open the app i see it lists the game is using the dGPU. At some point the Activity Monitor will switch from grey to colored to properly indicate that the dGPU is in use.

Later, after I close the game the Activity Monitor will remain lit up, even though it's correctly showing no programs using the dGPU.

Should i just accept that this app is pretty awful?