Yeh I'm sure I've seen microcode updates pushed via windows update before.. Due so a security issue... Can't remember the details as it's going back a while... Windows 10 era.
Yes, those are controlled by mcupdate_genuineintel.dll (Intel) / mcupdate_authenticamd.dll (AMD) if you remove those files out of the System32 folder it stops the auto updates on both platforms and then you can run a UEFI/BIOS defined MC if your MB supports those features.