Just copying this from the discord channel to remind myself to check this later.

Androsa - Today at 4:43 AM
Also, the progression barrier is showing, even though my progress should have banished this (only happens in some parts of the swamp). Nothing is happening though

Stalkob - Today at 4:43 AM
Yeah
I had the same thing happen to me
I just walked into it a bit and it dissapeared

By their description, it happened when they had not progressed past the labyrinth (opening the fire swamp). In some parts of the swamp, it would show the weather effect even though they had cleared the lich tower.

Perhaps the client is detecting that the player has not cleared the fire swamp, so it needs to show a weather effect, but the player is standing in the swamp, so it shows that one?