Looks like your GPU could be on it's way out..
Remove it from your pc, clean any dust in the cooler and from the fans if you haven't already..
If it's the same when you put it back, try changing the thermal paste and make it a good quality one (Arctic Silver 5) for example..
You could try a different cable and try it in a different PC too..
AMD Ryzen 7 3700x, Asus Tuf Gaming RX 6700 XT, Asus TUF Gaming x570 Plus, 32gb G.Skill TZ neo 3600mhz, Samsung 980pro 1tb NVME, Samsung 970 EVO Plus 1tb NVME, Lian Li Galahad AIO 240mm, Antec Titanium 1kw.