Hello, I have a question, yesterday I had different resistances in my character, has there been any event these days that lower the resistances, because yesterday I was looking for a small charm for light resistence, and today I have already 75 res, I do not understand.

Your resistance is based on your gear & charms, and there’s the anya quest in each difficulty that also gives you resistance when those quests are completed

You get lower resistances in nightmare and hell. Maybe that's the reason.