Dualboot with Linux Mint and Win 10 Pro. How to stop Windows 10 from overriding my boot order in BIOS on every restart?

My PC (self built with Asus motherboard) was a Linux-only machine until I added a fresh install of Win10 on a separate drive using Ventoy. I use Linux Mint 95% of the time and want to automatically boot into Linux, preferably without showing GRUB. I have Fast Boot turned off, and I keep resetting the order in BIOS only to have...