Trash talking, actually is fine.
But there's a difference between trash talking someone for doing something stupid once or twice giving you a lead, like "nice play lux lol" after she failed her skills, or "thx for the leash" when you pull off an objective steal,
and then there's flaming someone, spamming insults into the chat, any form of "kys" or any other hate speech, spamming "bad" "trash" "report x" "x is so bad" "dumbass".
So keep to trash talking, even insults have to have some form of friendliness, it's called sportsmanship.
vs
, when I’ll say something like, “The tribes of Shurima rise against you, Azir!” when the match starts. After the match, I might say, “The time of Emperors is over, Azir” if I win, or “The people will never surrender to your rule!” if I lose.