if it's on water they could probably set a higher roughness cutoff in general.
while this is in theory a smooth material, the ripples have a similar effect as having a rough surface... and if it runs fine with such a large reflective surface and that much scattering, they can probably apply it to more surfaces.
makes me wonder if they used the wrong value on accident tbh lol...
and it wouldn't surprise me either, after hearing how devs sometimes forgot to turn on Anisotropic texture filtering on PS4 back in the day, because it wasn't part of the engine's default preset for PS4