Riot Scruffy came out with some behind the scenes patch notes that confirmed that League of Legends matchmaking rating was indeed bugged but was not fixed until 11.2.
Patch 11.2 has already rolled out but it's currently not clear whether everything it has in store has gone live. For example, it's known that Viego didn't launch with the patch immediately but his release of January 21, 2020, didn't leave the fans waiting for long.
Another interesting update is the MMR fix that will probably make life easier for some players. Namely, it was discovered that MMR was bugged and League Point (LP) gains in Ranked were too low, compared to the losses.
This lead to some players gaining less LP for wins than they lost for defeats even if they were on a winning streak. Essentially, it appears the bug blocked MMR progression in the background and some players would get stuck on the ladder with no fault of their own.
That said, we did just leave the preseason behind us and with the chaos these early stages of a season cause in Ranked could possibly have led to another year of inflated false positives in support tickets regarding the MMR and LP behaviour.
Still, Riot Games told players that the system works fine on several occasions, which didn't paint them in a positive manner when they admitted the MMR was indeed bugged.
It takes guts to admit to mistakes though, so credit where credit is due. Mark Yetter didn't specifically say when the fix would roll out but if Ranked starts feeling better after the latest patch, this is what fixed it.