I have minor blue-yellow colourblindness, and while it doesn't really affect my daily life, it definitely affects my gaming experiences and can be absolute hell at times for mechanics in fights. Even in NORMAL content if I'm being honest. My static on Thursday had to literally sit there for 20 minutes to help me figure out how to read escelon 1 in EX4 because it was the same issue I had in M4S being too much of the same identical colours. I don't have much issues with the red on red in that fight, but I know others that do have issues and I definitely think it's a bad look from SE for sure.
I suffer from severe chronic migraines as well, and have various disabilities that make processing fights an absolute nightmare in raids (I probably shouldn't raid, but I'm stubborn and want to prove old guildmates wrong from WoW who said I would never be able to do raids like this). The VFX in fights have been getting progressively WORSE ever since DT launched. LHWs was an overstim nightmare, if I hadn't been relying on callouts in M4S especially due to colours and bright flashes, I would have been 100% throwing up during prog and reclears. I was having similar issues in EX3 as well due to some of the colour and VFX decisions. Consistent migraines after progging a fight due to VFX and colour designs on fights really isn't a good things to have players have happen.
I had some knucklehead say that "visual clutter is what makes these fights hard, lol, removing that would make these fights too easy" and while I agree SOME clutter should be there for difficulties, being there in excess like it has been recently isn't how it should be. M3S towed the line of almost too much given that it was almost as problematic for me as P3 back in Pandae, but M3S had a decent enough balance with the fuses and the like. I loved M3S (looking forward to M7S too), but that orange on orange was a nightmare. Visual clutter with layering the same colours on each other, especially when you have disabled players like me and others here in these replies who love this game and hard content; really isn't how fights should be designed.
It very much feels like alienation to a disabled player base that adores this kind of content, and it hurts me to point that finger toward a game I adore so much. They either need to add a filter that dulls some VFX or improve their accessibility settings across the board to give a better experience for those of us who need that extra hand for playability.