This Make No Sense

Alright I'm confused. Every time I win, my LP gained per win goes down. Despite having a positive win rate.

I'm gold 3 in solo/duo but I'm iron 1 in 3v3 because the LP gain just keeps decreasing each win. It went from +20, to +17, to now +12. Not sure if this is a bug or just the system intentionally trying to keep me in a league that I don't belong in.

Here's the game that I got +12 LP. You can see my wins vs losses and the type of KDA's that I get in these games.