Heat build-up: EG25 or SOC?

[CloudHackIX]

A lot of it is the current software. I put PostmarketOS on mine, but with XFCE and for the most part it runs very cool, even while playing an MP3. The same configuration but with Phosh or Plasma Mobile causes the phone to overheat and lock up. I think the mobile software just needs some work since it's very new.

My confusion is that it seems as though the kill switch should be preventing the EG25 from receiving power... so either it's failing to do so, or the shield is also radiating heat from the SoC.