Today I was editing a video when I decided to look at my CPU temps, and I saw the CPU was at 90º. When it’s idle it’s arround 55-60º, but when I play some heavy videogames or edit videos (I don’t do it often) it gets to 90º. Should I buy a new CPU cooler? (I have a Ryzen 5 3600 with the stock cooler)
No. I had Ryzen 5600 and it was working without problems with stock cooler. So your CPU should be fine. Replace thermal paste and you’re good to go.