Most of us have seen it or fall victim to it.
We spawn in and see someone shoot down an allied bomber/attacker or more rarely fighter at match start. In the first 2 cases, mostly to “secure” their ground kills/bases.
Since you are already working on implementing a system to forgive these players, I would also suggest implementing a system to punish them.
My suggestion would be to give the player in the first 5-10 minutes the ability to punish the team killing player. This would result in him being killed by the game/system and the victim gets a respawn. Therefore, if you try to stop a teammate from bombing a base and team kill him, you get killed and can not respawn, but the victim can and grind some money and RP.
I would also like to add feedback on reports. If I report a player give the player feedback what happened when the report has been dealt with.
If I report someone for racial slurs in Overwatch I receive most of the time a message telling me he was banned. This would also help players to understand the report system.
Yes you publish lists periodically but I, from my perspective after 10 years, have no trust in the report feature and think it is just useless to report people. You probably have to team kill many players or gather a huge amount of reports to be banned for a short time or forever.