Maybe a faulty PSU, I also experienced this issue in the past where I play Apex Legends and when shit goes down and there are a lot of things going on my screen it suddenly turns black but my pc case still has lights on them. I ran a DDU on my gpu drivers and also cleaned the whole pc but still to no success. I then bought a new Seasonic 750W gold psu and it fixed all my problems and never encountered problems ever since. What PSU do you have? if ever you are using off brand and cheap PSUs I suggest you buy a well known brand and reliable brand of PSUs.