Thanks, I'd greatly appreciate hearing of what you discover.
What we know so far is that something is causing the EFI "Boot Options" (i.e. the entries visible in the EFI Boot Manager) to replicate until eventually the VM's EFI NVRAM runs out of space and the VM fails to boot. It might be a few snapshots or a few VM reboot cycles before the problem can be first seen as multiple entries in EFI Boot Manager, and it might be many more snapshots or reboot cycles before the VM fails to boot due to insufficient NVRAM space.
A number of the instances of this failure that we've seen here (maybe all of them?) have Veeam in the picture in one way or another. I haven't been able to replicate the problem here at VMware, although I have not yet had the opportunity to try with Veeam to test if there is an interaction there. Your feedback suggests that I should definitely look more closely at the Veeam angle.
Please do keep us posted on your findings!
Cheers,
--
Darius