I get migraines where my vision is disturbed so I made a vid to illustrate what it looks like in Blender. It’s fairly accurate.
I 've been through many of those, not with triangles but less defined shapes, pulsating and changing in hue. The first time I thought I was going blind. I know now that there are quit common and mostly harmless, but they freak me out every single time.
Assume that lens aberration, pixelated screen in combination could cause this… studies to do.
I’ve become photo sensitive because of working hours in low light environment (indoor LCD). Also got migraines. Now i exercise my eyes and got better.
My triggers are changes in light like it becoming suddenly cloudy and too much caffeine.
That is vaguely like how I experience sound.