What matters is this, if you see that warning, something is wrong with your behavior and it is now risking you to get in further trouble. The warning is exactly that… a warning. Carefully think about what you are doing that could make other players upset and see if there is behavior that can be changed. Note, some players will get upset and report others regardless, but as a player of over 4 years, I would have been actioned by now with my known behavior. For example, I typically pick Pharah in many of my Competitive matches and often don’t switch if the opponents start to bring in hitscans, I only switch when I decide my Pharah is not working. Quite honestly I am rather a one-trick Pharah and it does make some teammates upset, but its how I like to play, and I have never even come close to a warning. I am very confident the report system is working to identify and stop consistent disruptive behavior. If you are actioned (which right now you are not actioned yet obviously), I promise you it will be due to consistently disruptive behavior.
Once again, as a MVP I talk with Customer Service quite frequently. Once again, what matters is this, if you are consistently disruptive, you will be actioned.
“Toxic” is a very ambiguous term and I avoid it. More likely your warning stems from multiple matches across multiple days, but only you can evaluate your behavior across multiple days.
The report system has been in place for PC players since game launch, and for consoles well before this community manager response was made. Trust me I document everything the developers have said. I do this for the community and to keep Blizzard accountable just as I want the community to be accountable for their own actions.
In the end, what is important for you GiantDwarf, is that you have seen the warning. I must imply that you are not in trouble yet, but all you need to do is simply provide a positive experience for your teammates.