Similar thing used to happen on my Sapphire R9 270X back in the day - would black out for a second or two randomly during the day several times, regardless of what was going on on the PC (be it games, videos, or browsing). However, this problem went away the moment I changed my surge protector (power strip), since it had been acting up every once in a while, so I suspect there might be something related to power issues here.
W10Pro (22H2)|Kingston A400 240G|ASRock B550 Phantom Gaming 4 (L2.71)|Ryzen 5 5600|ID-Cooling SE-225-XT Black V2|nVidia RTX 3070 FE 8Gb|XPG GAMMIX D10 [2x8GB] DDR4 3200MHz (XMP)|DeepCool PK700D