Adding my support as a photosensitive person who's had issues with flashing effects in specific duties. M4 in particular has been the worst for me in recent times; I walked out of my first clear feeling extremely ill after having to do multiple pulls to clear, and even recently I was thrown in via raid roulette and my options were to either drop out and take a penalty or perform poorly due to being flashbanged and risk feeling ill again. Even then neither option is fair to the players I was matched with, as they would either have to wait for a replacement or put up with my dead weight.

Other notable duties that I recall having photosensitivity issues with include E5, Tower at Paradigm (which also gives me motion sickness), Tower of Zot third boss, and Hydaelyn. I'll also note that, surprisingly, M5 Normal didn't impact me much but seeing bits of M5S prog on streams kind of guaranteed that I'll probably not be able to prog that in earnest.

As an aside, although I'm not colorblind, I admittedly have issues reading the Puppet Bunker-esque expanding spread mechanic during the third boss of The Underkeep because the floor is so low contrast that I struggle with discerning a safe spot until the last moment.