This is called match making rating it’s been used in videogames for a very, very long time. For reference I have a 4 year old kid and I was fully aware of how mmr worked when I was 15.
A quick Google search would do you wonders but I’ll help you even more.
You’re on such a bad losing streak that the game doesn’t think that 4-2 did anything. If you’re earning low points for wins it’s because your perceived skill level is at your CR or lower.
You need to start winning more than you lose consistently.
Your actual rating moves based on where the MMR determines you should be. If you don’t want to get +1 at 1300 you need to show the game you don’t belong at 1300 by consistently smoking everyone in the lobby
Side note for all the mads, this is why you’re not being held back by boosters because their MMR will sky rocket fast. If you 6-0 your first lobby you’re like 2200 MMR the next game