Change boot order in UEFI and then save your changes. It did the trick for me last time windows screw me over

Hi I am not a linux pro, but for me a quick fix what worked was to disable Windows boot. basically everytime windows boot it puts itself as priority, but cannot any more this way. I would then use the grub menu at boot to select what os i needed. I use mint but since both are based on ubuntu should work in the same way. found this online, more or less what i did: https://unix.stackexchange.com/questions/241809/grub2-gone-every-time-i-boot-windows-10 https://unix.stackexchange.com/questions/68581/how-can-i-prevent-windows-from-overwriting-grub-when-using-a-dual-boot-machine

My solution to this was to just set the boot order how I wanted it and then lock it from BIOS

My solution years ago when windows used to do this to me with a dual boot was to move windows to a virtual machine instead, which works great for me!

Would recommend as much ram as possible though. I find performance great with 16gb of ram to share between host and the vm.

Windows updates would often mess up boot prior to me switching. Very annoying.

I had a similar issue, and no changes made in Linux would stick. Bootice is a Windows program that allows you to make changes in UEFI boot order and was the only solution that worked for me. Good luck!