Drawdown FPS on my laptop (Fortnite)

In General, bought before NG laptop ASUS X570ZD - mediocre gaming laptop: Processor - AMD Ryzen 5 2500, video card - GeForce GTX 1050 2GB, RAM 8GB. Only after purchase you can play on high settings with resolution 1920на1080 stable 60 fps! Performance gradually fell and now you can't play even on low fps on low and on average 70 every 2 seconds drawdown to 30! What could be the problem? PAMAGITI!