Every time I’ve come across this it’s because windows restore points have been disabled for some reason, or the only restore point happens to be from when it was first installed. Other times it’s been when there are 2 hard drives installed and it somehow shits the bed and installs the bootloader to one and the os to the other, or upgrades to one disk but leaves a half valid install on the other, then boots the old install. Generally getting confused about multiple disks