xalAn osu developer found that Windows 27881.1000's libc says that pow(-1, 2) = -1. Poking around in bindiff reveals they tried to add an optimization that skips the main approximation when the base or exponent is 1, but screwed up. Woops!
osu issue: https://github.com/ppy/osu/issues/33948#issuecomment-3026432343
issue they opened on dotnet: https://github.com/dotnet/runtime/issues/117233
