From the error it looks like cores 1 through 7 returned a different value for a register than that for core 0. Most likely this is a CPUID instruction call or a read of a MSR for CPU features. I don't know why core 0 would have a different reading from cores 1 though 7.
Fatal CPU mismatch on feature "Intel processor platform type identifier"; cpu7 value = 0x1004195c, but cpu0 value = 0x10041a5c
Basically two bits were flipped. 0x9 = binary 1001 while 0xa is binary 1010
After rolling back to ESXi 7.0, is the microcode still version 0x12d? It might be a microcode/BIOS update problem somehow didn't cover all cores.
I think you can check microcode level from ESXi command line or from a vmware.log of any VM and look for ucode.
