Sorry for my bad english, i will try to explain you this bug.

When you make a win command on a trainer, for example a teleportation. (/tedit add win tppos @pl x y z)
It can provoc a freeze during the fight because the command is launched before the fight is finished.

To test that i have made a broadcast on a trainer (/tedit add win broadcast test) and the broadcast was launched before the end of the fight.
I think it's because when a trainer win, a log message is send to the server to say it.

However the player is again in the fight because he need to skip message like sturdy abilities, sandstorm etc..
In fact, this bug is most common when the trainer's pokemon who kills the player's pokemon has an ability like Sandstorm or sturdy because we have more message to skip before the end of the fight

A screenshot of what happens when the fight bug:
https://ibb.co/j1HiWK

This bug can actually be fixed if you change the default value ( for example i set 2000) but i think it needs a fix.
Thank you to read this!

For anybody wondering -- this may be a Pixelmon bug, which is why I requested it be posted here. I'll check it later.

Thanks for the report!

Another detail:
when a player doesn't past all message ( like sturdy ...) and just wait, the bug is always provocated.
So i think it's because the win message is send at the server directly when a player loose or win and not when a player has read all messages.
So i think that the win/loose event is being fired too early now

I just compared 6.3.2 and 6.3.4, but the timing of the event has not changed. I'm not sure what's causing this at the moment, but will pass it along to internal to see if anybody there knows what's up.

Keep an eye on the ticket!

This is now being looked into on the sidemod's end.