I had a 2070 Super in a Dell XPS 8930 SE case, not known for great ventilation. The 2070S would run in MSFS at 83 to 84 deg C with a thermal limit on the GPU of about 89 deg C. Now I have a 3090 FE that’s too big for my case so it sits outside in a riser stand. In a room that’s 81 to 86 deg F (27 to 30 deg C), it’s hard to get the 3090 above 61 to 65 deg C in MSFS (it’s thermal limit is 93 deg C). At the 3090 use temperatures, its fan is only running about 1,000 rpm whereas, IIRC, the 2070S fan was running close to 4K rpm. If I’m not simming, the 3090 fan never runs (0 rpm) whereas the base speed for the 2070S fan was ~1K rpm. So I would agree if a 3090 conked out, if it’s otherwise well-ventilated, there was likely a built-in hardware defect.
Edit_Update: I noticed the OP’s emphasis on unleashed frame rate. I don’t think I’ve set any framerate limit and I can do 90 to 100 fps in an Icon A5 over Mann Gulch, MT - a low or non-existent photogrammetry region. 60 fps at 1500 ft, ~100 kts over Manhattan (a high photogrammetry region) - I’m running at ~97% GPU usage according to the Xbox Game Bar stats using ~all ULTRA settings at 1440p. So I’m close to maxing out the GPU as I should be doing and it’s not burning up.