Lets throw out the word toxic. It's too vaguely defined and everyone has a different meaning for it. Talking in terms of 'toxicity' will lead to confusion and irritation for both of us. I'll talk with you about specific behavior though.
There are a wide variety of behaviors that Riot considers unacceptable in their game. Some of which are:
- passive aggressiveness
- bigotry
- hostility
- hate speech
- harassment
- intentional feeding
- antagonizing others to receive a 'funny' reaction from them
- etc. (other similar behaviors)
Now I personally think that each type of behavior should have it's own tree of punishment, so that a player who gets a 14-day ban for hate speech will not then be escalated to a permanent ban for passive aggressiveness.
Unfortunately Riot does not have a system that accounts for this sort of thing, so we wind up having cases such as yours where you likely had one type of behavior earn you the 14-day ban and then even though you stopped that behavior you still exhibited others that were also considered unacceptable and thus received the next tier of punishment upon being reported for those behaviors.
With the exception of hate speech and intentional feeding, you would normally move up through a series of chat restrictions, then to a 14-day ban, and lastly a permanent ban. The exception being that int-feeding or using hate speech results in immediate escalation to 14-day ban.
When you have recently had a 14-day ban you are on a sort of probation, it won't matter what sort of negative behavior you exhibit, nor how major or minor it is. If someone reports you and Riot sees any sort of negative behavior, they give you the boot.