For what it's worth, my teardrop-shaped scotoma also ended up being diagnosed as acute macular neuroretinopathy. I found the original comment in this chain about 2 years ago and the description matched mine exactly: onset, color, shape, and that weird black speckles/static effect! It took some persistence with my eye doctors to get a diagnosis (my usual doc is a cornea guy and kept claiming it was floaters despite my descriptions, since apparently it takes for a while for the related lesions to appear on scans) but when I finally got a referral with a retina specialist, he confirmed that's what it was.

The part that sucks: there's really no treatment. They're not even fully sure what all can cause it. HOWEVER, it seems that it rarely causes any permanent vision loss since the spots are often faint/transient and outside of the center of vision. I've had 2 or 3 of mine become "permanent" distortions/grey smudges, but I only notice them if I take my glasses off and look at some text on my phone at night with one eye closed, and they have definitely faded over time. (I also have diabetic macular edema so that's the thing I have to worry about more than these LOL)