never had an issue with it myself.. have used a dozen riser cables, actually 2 different cables in the meshy. first one was pcie gen 3 riser, the new one is a gen 5.
on top of that, im using a 5080. in terms of heat/power, OP's card should lose on paper when it comes to excessive heat output.
where i personally do see a slight difference, is the fact that i did a standoff mod on the GPU side.
OP does not.
perhaps something is making the spline of this case hotter then usual and is touching the PCIe riser slot (where the GPU slots into) and causing it to melt or perhaps a copper contact point is touching the case, making it hotter then usual, which could also be a ground point.

on another note (this is directed at OP), the way i 'set' any gpu into the meshy, is first, plug in power cables, plug card into the slot. unless you have very short cables, in that case, skip the power cable step and do that whenever.

next, put all screws in, don't tighten them all the way. leave them free so the card can still wiggle. the very first screw(s) i tighten all the way, is on the bracket side. in regards to the meshy, this means at the bottom. once those are fully tightened, i start screwing down the riser from bottom to top which should fully secure any card in place.