I don't know why this is. I don't even think my MMR is that low. I just won a solo/duo game, me as a Plat 4 player, where all 9 other players were also Plat 4 and I only got 14 LP. I lost a game recently and lost 22 LP against pretty much equal opponents.
I don't know why Riot gives me so few LP. I had something like a 54% winrate in season 8 on about 250 games. Sure, I had a bad losing streak towards the end, but that doesn't justify my LP gains / losses. Playing in preseason, I'm 4-1 wins / losses on solo/duo and I can't seem to improve MMR-wise.
Anyone else experiencing this? Is this a product of the new ranks and me being promoted from P5 to P4?