Same problem as first post, but I had installed with Ventoy 1.0.99. (Proxmox 8.2-1).
I came back to balenaEtcher with ISO on Sandisk USB.
Secure Boot (Standard) ON is supported by balenaEtcher, no need to juggle On/Off, leave it permanently On.
TPM On as well and everything works.
(Ventoy is...