The very first patch of it, 5.22: https://na.leagueoflegends.com/en/news/game-updates/patch/patch-522-notes
Well, just read.
Marksman update ✓
Mana changes and base AD changes ✓
"Game pacing changes" (aka fuck late game, there are no longer distinct stages of the game anymore, and everything's a 20 minute stompfest) ✓
Ambient gold increase ✓
Gold for kill increases ✓
Changes to fuck up and over power bounties to add even more gold to the game ✓
Buffed damage to towers ✓
Removed shield towers from the game ✓
Turrets lost 100 armor and MR to gain "2 armor and magic resist per minute, up to a maximum of 30. Outer towers begin scaling at game-start, Inner towers at 15 minutes, Inhibitor & Nexus towers at 30 minutes." some armor some of the time, but with 20-30 minute game averages, the inhibitor and nexus towers no longer functionally have resists ✓
Over doubled the gold value from towers (outer towers used to be worth a total of 150g, every other tower was merely 100g) ✓
BULLSHIT INSANEASS MOTHERFUCKING MINION CHANGES I mean seriously, this change alone did so much to increase snowballing everywhere and end out games. Also fucked up minion wave management for years.
They even nerfed
some more, removed
and clairvoyance (which seriously doesn't even have its icon file on their own website anymore? fucking really?)
Then they removed: Avarice Blade
Crystalline Flask
Elixir of Ruin
Mana Potion
Poacher's Knife
Ranger's Trailblazer
Stealth Ward
Sword of the Occult
The Brutalizer
Twin Shadows
Zephyr
Then they did they're piss poor item re-balancing pass. . .
Basically across the board buffs to AD items, increases in costs and buffs to a few AP items, and some QoL buffs in better build paths, but then pretty much a dumpstering of tank items which shoehorned them into being antimagic (and thus weaker to the ADCs who just got reworked, and buffed in items across the board)
They also changed up the jungle, jungle items, support items, THEY GOT RID OF FUCKING WARDS
added trinkets
Added keystones to masteries and removed all the choice and variance in the old runes
It was just actual shit. Reading the change log makes me livid every time, and its been over 3 years.