The point of looking at these betas is to run down bugs (e.g., RAW behavior) and confirm changes (e.g., inverting). The three beta releases all have the same rev. number: 1.21. The only hint about which version is which is to look at the zip files' name. Better to use r1, r2, etc., when it comes to tracking changes between the versions of V1.21, than reference long file names.
There apparently are some " failure to communicate"problems in the numbering of successive fws from Sjcam teams; I look at the date of the fw to see if it is a latest one.
If I want to get heavily into raw shooting, the Yi 4k + is the real deal!