[1] Team chat works again.
[2] Team chat shows your team color now instead of raw tags like <red> or <gradient:...>.
[3] Team chat stopped eating messages with "pass" in them (compass, passed, etc.). It only catches actual "password" now.
[4] Team PvP toggle sticks now. Turning it on could get reverted by a background sync a second later, so teammates still couldn't hit.
[5] Ender chest hardened against dupes. Two people can't open it at once, and it's now snapshotted right before saving so a mid-drag item can't land in two slots.
[6] Works on Paper 1.21.x and 26.1.2, Folia, Purpur and Spigot.