I play on a laptop and have been playing on it a for a while.
During January 2021, some update came and my game has been wonky ever since.
I am playing on 70+FPS consistently then all of a sudden, the FPS will drop at 20 or so and stay there for the duration. Only way to bring it back up is to close Borderlands 3 and relaunch it.
Thermals are not an issue, trust me, I have thoroughly checked it.
Laptop : Predator Helios 300 with RTX 2060.
This only happens on Borderlands 3. I have no issues with any other games.