We encountered a game 'POE2' rollback issue when playing Breach Tier 5 content.

Today, I was playing Breach Tier 5 content with a friend. Along the way, we were killing monsters as usual, and when we reached the reward drop area, I got a Divine Orb.
After that, we proceeded to kill the boss. Once we defeated it, I suddenly got disconnected to the login screen.

When I logged back in, I found that my character was returned to my hideout, and all the loot I had collected was gone, including the portal to the dungeon.

In the end, I lost the key without receiving any reward. This issue has happened to me twice in a row now.