Is it possible for anti cheats to hack your UEFI?

I was on another forum and was suggested that anti-cheats on video games has the ability to hack your UEFI and to stay persistent. Is this true? If so how is it possible when the operating system itself can’t modify UEFI, only the user can if they go into the BIOS settings themselves?

If it stays persistent is it possible to boot into msdos via live usb drive and to flash the bios/uefi firmware into the motherboard, lets say gigabyte?