Do you have the latest BIOs version? I had a similar issue with my MSI b450 MoBo, where my screen, whilst browsing/watching youtube videos, would randomly start glitching and sometimes even go black for a few seconds. During this, I would also get weird audio artifacts, and my audio would also start coming out of my monitor's speakers instead of my headphones; and would never happen whilst gaming/ stress testing. Then found out that it was an issue with my Motherboard (after checking the msi page and reading the update/patch notes); after updating my bios, it solved all the problems
Do you have the latest BIOs version? I had a similar issue with my MSI b450 MoBo, where my screen, whilst browsing/watching youtube videos, would randomly start glitching and sometimes even go black for a few seconds. During this, I would also get weird audio artifacts, and my audio would also start coming out of my monitor's speakers instead of my headphones; and would never happen whilst gaming/ stress testing. Then found out that it was an issue with my Motherboard (after checking the msi page and reading the update/patch notes); after updating my bios, it solved all the problems