I don't think it's the problem with my laptop because it's a gaming one:
My baby Laptop Gaming ASUS TUF FX505DD-AL062, AMD Ryzen 5-3550H up 3.7GHz, 15.6" Full HD, 8GB DDR4 2400 Mhz , SSD M2 512GB, NVIDIA GeForce GTX 1050 3GB, windows 10 home 1909, Stealth Black:
My fps decreases:
After a few seconds it returns to normal:
Settings from the game: