Visit acheron ruins. Take the left bridge. Move along the lava river to the left of the bridge on the grass. Get to the highlands where the character can partially walk and crawl. Carefully move to the inaccessible ladder and climb up. Jump towards the river to avoid crashing. Jump into the lava. You will be burned a little and you will find yourself under the lava (at the bottom of the river) near the edge of the world (it is also visible from this area). Your journey is over. On one side you will burn, on the other you will be limited to the end of the map.
Unfortunately, I took the screenshot incorrectly and copied the coordinates in order to provide accurate data. According to the game map, the coordinates are approximately x 270 y 485. Climbing again is fraught with a violation for death, so I don’t want to repeat it.
705.0 592.6 y 183.8 4022
Summary
https://imgur.com/uxnVTi4
Maybe it’s not really a bug. Features of game mechanics (engine) and terrain creation.
This happens when you explore the map looking for something unusual.
For example, on the other side of the lava river, where the entrance to the acheron ruins (outside) and the secret item is a “non-material” stone that allows you to ascend and descend in alternative ways.