To be fair, for your last point the timeline was actually
"Yuumi is garbage"
riot does this:
"yuumi is broken"
many patches undoing those absurd buffs ensue
This was intentional, you know. We knew we were almost certainly going to need to pull out all those buffs and more since we predicted her release balance state to be long term overpowered (est 55% winrate), though we definitely underestimated how bad players would be at her in the first few games. At the end of the day it's important that the game be balanced for now rather than for 3 months down the line, and those "absurd buffs" got her from 32% winrate to 38% winrate when they were micropatched in