here are some naming rule that you can identify bios in which status
Official bios, it will be 0x0x or xxxx, e.g. 0806, 2204 and can download from official website, but there will have a time delay between it build and release, sometimes you can download it from ASUS RD, but can’t find it from official website becasue bios is on internal testing and need time for approval
Test bios, it will be only 00xx, e.g. 0040, 0051, modify for improve compatibility or system stablity
Special or meida reivew bios, it will be 9xxx, only offer for specific using to solve issue or for media review before it official release all bioses will based on official bios and modify for improvement