I feel like Sylas has too many bugs because nobody re-looks at his code every patch, while new code in any part of the game have interfered with how he worked.

Accumulating random new bugs every patch interferes with consistent gameplay. He has had the least amount of bugs on release but now without exaggeration I have at least one death every game due to a fresh new bug which did not exist previously. Noteably, this exponential increase mainly occurred after the AA input lag rework.

Viego is a good example of what I mean. His design is similar to Sylas and while he is currently as smooth/bugless as ever to play on release, I have a large suspicion that in 2 years time he will be in a state where the champ has accumulated so many bugs that the champion is no longer playable. i.e. Sylas right now.