The bug:

When a mob in a colored team kills a player, the corresponding killedByTeam.'color' doesn't increase.

How to reproduce:

1. Create a team with a color by executing the following commands:

   /team add red
   /team modify red color red

2. Create a scoreboard objective that increments when someone on that team kills the player:

   /scoreboard objectives add killedbyteam killedByTeam.blue
   /scoreboard objectives setdisplay sidebar killedbyteam

3. Summon a mob on that team:

   /summon minecraft:husk ~ ~ ~ {Team:"red"}

4. Let the mob kill you.

Expected result:

The scoreboard objective would increase.

Observed result:

The scoreboard objective did not increase, even though a mob from the colored team killed the player.

Original description

So I was messing with commands and scoreboards and teams I made a scoreboard to check if a player has been killed by a team I used the red color and set the teams color to red and It didn't work I spent about half a hour trying to get it to work