FPS drops. What to do? (Far Cry: New Dawn)

Faced such a problem: fps is 100, then 20. I do not know what this is connected with. The funny thing is that when I start the task manager, the fps bounces back. PC:
Video card: Radeon RX 590
Processor: Intel core i5-10400F
RAM: 16 GB
Maybe someone knows how to solve this problem and that the FPS is stable (at least 50-60)?
Ps changing graphics settings doesn't change anything