With today's server save, Tibia have released a new client version. Among others, they changed the following:
The boss Grand Master Oberon is accessible again.
We have temporarily disabled the Frame Rate Limit slider for the Mac client.
The loot table of the Crazed Winter Vanguard was slightly adjusted.
Tibians can no longer be turned into Snowman while standing in a protection zone.
Removed the protection zone block check from several portals and teleports that got implemented with the last winter update.