Hmm I think it's this game? A lot of the jaggies seem to be from low-rez geometry for the spell FX. Though the textures do get blown up pretty large too. https://www.youtube.com/watch?v=uY206fXsa8o?t=252 I'd suggest trying a test of just Bilinear upscaling the texture to 2k, and adding some noise. See how big the pixels of…
Sometimes UE just starts to do weird disco pixels on certain mip levels of certain textures. restarting, it'll clear up. If it's the same thing, it'll just creep up on occasion.