devtrackers.gg
That's a good question, I'm not entirely sure. My source was this comment.
/u/psyonix_devin Is a match considered "concluded" once it hits the 0 second mark, or is it once the server kicks everyone off?
The latter, so if a player says something that would merit a chat or game ban after 0:00, it still gets accounted for if someone reported the player at any point in the match.
A follow up to that:
If I report something in chat that pops up, then the person follows up with something far more offensive, does the report only show that was said prior to the report or will the entire chat log show up for after the game?
An example being: Person says something offensive and harmful to the community that would be caught by reporting. I report it. They follow up with dropping racial slurs, bigotry and other extreme forms of hate speech. Is that seen by the report I sent in before it happened or only what is sent before the report will be seen?
Once you a report a player, the entire chat log for the match -- including after the clock hits 0:00 -- is sent for review. Anything a reported player says is taken into account.