It was merely to tone down your wrong, as you said it in the way you think only you were right and we were all wrong. I still need an actual prove, something like an external camera recording in this order:
- Boot in GRUB
- Choose Windows
- Do Windows update
- Reboot
- Show somehow that it overwrites the ESP instead of just changing the boot order, Windows has
mountvol /sthat can be used to mount ESP to check it or use something like GParted live, there are many ways, but I need a real proof
Now this one I believe. It’s the same case as I said above, where the UEFI firmware looks for a particular boot entry that when doesn’t exist it adds automatically and set it as default, effectively stopping GRUB or any other boot manager you have from being the default. However, the ESP remains intact. Not overwritten by any means. One case that I personally observe on the spot, is when installing where people tend to just press next without reading what the page is about, and that’s how it ends up overwriting the ESP. Never once I’ve seen Windows update causing it.