Elemental resistances dropped by 20%, not from act penalty

I encountered an issue where elemental resistances dropped by 20% each, not due to the usual penalty after completing an act.

Previously, while equipping my gear in the endgame maps, my resistances were at 80% Fire, 76% Cold, and 76% Lightning. However, as I continued playing Tier 1 maps, my resistances suddenly dropped to 60% Fire, 56% Cold, and 56% Lightning, even though I was not affected by any debuffs.

What could be the cause of this? This feels like a waste of resources as I carefully calculated and crafted my equipment to achieve proper resistance values. To emphasize, this happened while in the endgame map system.

This issue occurred on December 17, 2024.

Account: lnwmo007#4403
Game: POE2