Fact check this before trying as I haven't used NVME SSD's yet and have no experience with them.
I think it was in my MSI MOBO Product Manual (X370 M7 ACK). It has 2 M2 interface ports between the primary and secondary PCIE ports.
I can't locate my manual at the moment but I vaguely recall something about if using a GPU whose dimensions would cover 2 PCIE x 16 slots that it is best to use the lower slot.
Came across some videos on YouTube were claiming that large triple fan GPU's were creating EMI interference for their NVME cards. That was back when NVME was fairly new and haven't seen such videos or claims like that in a while.
Stands to reason if those M2 housing points aren't properly shielded for EMI being that close to GPU's that can produce a lot of that in a small area could cause some issues.
Once again no experience with NVME cards but EMI I have dealt with in various electronic systems for 36 years and I know it can cause a lot of annoying issues in audio/video systems.