Before the Nov 14th update I had 600 customization credits I was saving up for a more expensive helmet. Ever since the update, I played only custom servers, but given that they don't award exp I decided to play a normal custom game. After completing it, I leveled up and got 100 credits, but it like replaced the 600 I had so those 600 just disappeared and I only have 100 now.
I'm not like asking for credits back or whatever, its a beta after all, but losing credits is a critical bug that should be addressed before the game comes out.