Sion is the best example of why you don't fixe bugs without nerfs on Champions that are fine

without nerfing them

His bugs basically made his Q/E not working, if you fixed them how can you possibly think the champ won't end up busted when he had ~~53% win rate before you fixed them?

In the past, whenever riot fixed bugs that hindered champions by a lot, and the champions were already good they nerfed them in the same patch

Aria of Perseverance Aria of Perseverance Fixed a bug where Power Chord Diminuendo was not reducing the target's damage. Power Chord Diminuendo duration reduced to 3 seconds from 4.

Noxian Diplomacy Fixed a bug where the Bleed didn't do damage Bleed damage reduced to 10 / 20 / 30 / 40 / 50 from 18 / 36 / 54 / 72 / 90 Bleed AD ratio reduced to (+ 100% Bonus AD) from (+ 120% Bonus AD)

You fixe syndra bugs syndra had 46% win rate before that, nothing is wrong

You fixe Sion bugs Sion had a bloody 5% pick rate and ~~53% win rate before that he was already viable and strong with comet bullshit E poke

now, you need to nerf his E damage and possibly buff Q damage to make Sion more skilled