This image is kinda similar to my experience. It starts as a very small spot, often just blocking a letter or 2 of a word I’m reading, then spreads out in an arc or rough circle.
One interesting thing I’ve noticed as I get older (40s), is that if I’m moving over a distinct enough pattern, like a tile floor, the area inside the aura updates slower, or lags behind the surrounding (unaffected) area.
Also as I’ve gotten older, the pain following the aura has thankfully gotten lows severe, and sometimes doesn’t happen.
In my experience the pain after the aura sometimes happens, sometimes not. But it’s usually not severe anyway, just an annoying constant headache that lasts for a while (hours) after that.
When I was younger, aura meant I was in for 4-6 hours of intense headache afterwards (aged 14-20s). But it reduced more in my 30s and is rare now in my mid 40s.
Same experience here. I’ve gone through many superstitions regarding it, like living near heavy pesticide use, eating potatoes, refined sugars, brain tumor…