They don't. I'm 100% sure of it.
I once was reported by three to five teammates and three to five opponents for int-feeding because they banned my champ to be an intentional dick, and within literally five seconds of match end I got a 14-day ban. It was in normals.
It's fully automatic, but it makes me wonder how people like me can get a ban after ONE game, and people like them can play an upwards of ten to twenty to fifty games without being banned for the same thing I was after one game. It feels sort of like a double-standard.
What makes it worse is that my game was actually filled with an interesting amount of cross-team chat about numerous things, with me included in the discussion, since the match already was a foregone conclusion.
The enemy team even said "Sorry you had such a bad day" and things like "I hope your luck improves" a couple times, even if my allies endlessly bitched at me for feeding. I heavily doubt that amount of friendly[?] discussion was included in their long list of int feed games.