In Medieval Empires, you might be losing prestige for several reasons:
Battle Losses: If you lose a battle, your prestige decreases. However, the amount lost depends on how close the defeat was—close defeats result in lower losses.
Unfinished Encounters: If you start a Map Encounter (like a wild farm) but don’t complete it before the timer expires (e.g., not claiming all the resources), you’ll lose prestige.
Daily Prestige Deduction: Every day at midnight UTC, 2.5% of your prestige is deducted but at least 100 (minimum Prestige is 0).
The constant deduction of player prestige represents player activity, so make sure to finish encounters, avoid battle losses, and stay active stay on a high prestige level!