Then after clearing the bearscape, once the main boss was destroyed, the portal to exit appeared and it was the same black dot instead of the usual portal :

Then 2nd oddity, when i moved on the portal to exit the dungeon, the minimap got covered by bunch of dots as if there were tons of new enemies out of nowhere :

Despite there was none, once i moved out of the portal tile, the minimap went normal again, filling with dots again when i went back to the portal to exit.
note : i don't use any shaders, their options are all disabled. Problem wasn't existing in previous version(s) for me