I don't think the generic ARM ISO is necessarily the cause. Since Windows upgrades to 25H2 successfully and then works normally after the automatic restart, the installation itself appears to be largely sound.
The more telling symptom is the repeatable cold-boot BSOD followed by a successful reboot, which points more towards a firmware or driver initialization issue than a corrupt Windows installation. I'd first ensure all Surface firmware and optional driver updates have been installed and check the BSOD stop code or Reliability Monitor for clues.
If the problem persists, I'd then try the official Surface Recovery Image for your exact Surface Pro X model. Unlike the generic ISO, it includes the complete Microsoft-validated driver and firmware package. If the issue remains even after a factory recovery, I'd start suspecting a firmware or hardware fault.
One thing that also caught my attention is that the machine reportedly became unstable even while creating the recovery USB before the reinstall, which suggests the problem may have pre-dated the clean installation.