In SERVER-54407 we bumped the required x86_64 microarchitecture to sandybridge but we backed out of that on macOS in SERVER-56728 because Rosetta 2 doesn't support AVX instructions, among others. Once we have native Apple Silicon builds and no longer need to rely on Rosetta 2, we can reintroduce targeting. We may in fact be able to target more aggressively, and bump to -arch x86_64h, per the comments and links in SERVER-56728.