I personally think you won't notice any difference performance wise, only in graphical comparison. Had a Meshlicious and sold it but not due to this reason, just change of case.

I got the PCIE 4.0 version in the first place, it worked, but sometimes GPU not detected, sometimes BSOD (even tweaked numerous settings). Bought a PCIE 3.0 riser after that, set in bios to PCIE 3.0 (b550 chipset & rtx 3000 series) and never had any issues after that.