That just sounds like it's manipulating your SR.
It kind of is. It's actually there to kinda deal with groups and boosting. Like, if you are being carried a ton while your stats are complete garbage, it's going to be hard to earn SR. If you do get a ton of SR but your stats are still garbage, the game is going to drop your SR a lot faster to reflect your stats. If you have crazy stats, it works the opposite and tries to dump you with SR until you get higher up.