If you went pink for 5 games from 1 shell hit, this is a result of multiple TK's across a short period of time. It is not a direct result of the one shell.
Do you have a screenshot of your "Detailed Report" tab, it will show how much dmg you did. This could have also occurred if you had a ship not spotted close to the ship you fired at and hit that ship multiple times as well as prior TK'ing.
Mahalo,
-Hapa
https://wiki.wargaming.net/en/Ship:Teamkilling
As I stated, if you were set as pink for 5 days, it doesn't have to be necessarily for the same day, if you TK'd a couple days ago then yesterday and again today, they will accumulate.
-Hapa
Yes sorry, I meant battles.
Here's the deal, how about try not to TK.... you are responsible for all ordinance you throw down range, if there are friendlies close to an enemy and you could hit them if you shoot at a target, then don't take a shot.
^^^^ this was my original response. If you would like for me to break down WHY you went pink for 5 days, PM me, I have looked at your game logs and know exactly why, but I don't intend to put your business out in the public.
-Hapa
devtrackers.gg