And yet it still gets hot. Then you add the fact it’s mounted to the rear of an ITX motherboard in a case that has it flat against a panel with zero direct airflow.
While generally thermal throttling in a standard case won’t happen due to case airflow and taking a substantial load to push the thermal guard, this isn’t true for ITX cases with restrictive airflow like this one.
Your right about them getting hot. I had a similar setup to OP in an sg13 and my hpEX900 would get pretty hot behind the mobo since there wasnt any ventilation or direct airflow hitting it. A temporary solution I had was using a thick thermal pad between the ssd and bottom of the case to transfer a bit of heat but even then it wasnt an ideal solution. Since switching to a slightly bigger core v21 my temps have improved dramatically, although performance felt the same.
Performance felt the same because the thermal tolerances for SSD's are much higher than most users might assume, OP should be absolutely fine with the way that they have their configuration setup.