1. Any other info from dmesg after rebooting? How far into the boot process is this? I assume it is not the initial use of the EFI partition because you are actually booting a kernel, and is the later mounting from fstab that takes place later in the boot process?
Edit: Are there a lot of other peripherals that could be taxing the power supply and causing a brownout of the NVME later in the boot process?

2. Given that you actually started to boot and then failed the second mount attempt (you couldn't even get the kernel to start loading if it was really corrupted), my thought is a failing NVME. It might not show up on an fsck because there is no actual corruption and it just intermittently fails to read.