Looks like a blanket tint to me.
And even if the lightning and lightsabers are isolated, mixing red and blue like that may become a seizure hazard so gotta be careful. Someone did a mockup of it on Reddit. I guess you could make it seizure-safe by leaving the background lightning flashes red or something close to it, but that would be kinda weird. If you make all lightning red this isn’t an issue and the only thing blue would be the lightsabers. Personally, I think making all lightning red across the series would be nice to color coordinate with the Dark Side using red lightsabers.
Okay, I understand, you guys don’t want red Exegol, you want red lightning. That’ll teach me to post before reading.