About frequency drops:
When PC on Idle it is normal that your frequency will drop like that. In perfect Idle scenario you would see only 0.9 and 1.2 Hz but you see the dynamic increase and drops because of some background task running and other stuff...
About CPU temps:
I have an laptop with 8750H and RTX 2060 and I have same temps as you even after thermal paste replacement (mostly 80-85º, battlefiled V is + 92º) .
About FPS drops:
If you have fps drops its for sure because of temperature, the best thing you can do is following:
- If you still have warranty and don't feel confident to open your laptop to replace thermal paste you can install Intel Extreme Tunning Utility and do a CPU under-volt, which you can test what is the best value for your cpu. This can drop some ºC and the problem will disappear. You can learn more about it here.
- Buy a cooling pad (this works better if your laptop have air entrance in the bottom of your laptop.
- Replace the thermal pad, this maybe the best option available.