Okay, looks like driver version is ruled out, and we were able to find out what the problem was. It looks like it’s triggered by buffs/abilities which cause you to cast light. (Example, blue glowing puffer, certain transmogs, etc.)
That bug is actually already on the devs’ radar. They’re working on it. Thanks for the reports. At this time, no more info is needed, but you can let us know if this is affecting you.