packet
Ping logic:
When you join a server, you always have 0 ping at start. However, if you are on a game like Practice and come back from a duel, you will keep your ping.
As for Matrix and Intave, they defy this logic. Intave though decides instead to fix it by sending ClientboundPlayerInfoUpdatePacket.Action.UPDATE_LATENCY to make up for the ping issue. Unfortunately, that leads to even more problems.