Add a thermal pad to connect the heatsink to the back cover and the thermal throttling will go away. Tons of tutorials on Youtube and it takes 5 minutes. I did

Add a thermal pad to connect the heatsink to the back cover and the thermal throttling will go away. Tons of tutorials on Youtube and it takes 5 minutes. I did it on my M1 Air and it doesn't go above 85-90C now.