5000 of my coins disappeared

before playing one division rivals game, witch i had an objective that gave me one pick if i wouldn’t let the opponents score 3 goals, i had 102k coins. after i won the game and open the pick, returning to main menu, i find only 97k coins. but i haven’t bought any player or stuff like that, some explanation? i know it’s only 5k but i find nothing from packs so at least let the game don’t steal my coins for no reason, i hope you will find something to do about it, thanks.