Hello! It's possible for your trophy count to decrease if you don't maintain your rank in the game. The trophy system in most games is dynamic, which means that your trophy count can fluctuate based on your performance in matches. If you don't actively play and win matches to maintain your rank, your trophy count may decrease over time.
Additionally, some games have seasons or periods where trophy resets occur. During these resets, all players may have their trophy counts adjusted downwards to a certain extent, which could explain why your trophy count decreased after a month.
It's important to consistently play and perform well in matches to maintain your trophy count and rank in the game. If you take a break or don't actively play for a while, it's possible for your trophy count to decrease due to inactivity or seasonal resets.