Gotta say, you really don't need to include time limited costumes to your game. It's just gonna create a drain on resources, esp in the long term and make a bunch of potential costumes be unobtainable to most of the player base.
Leave the gacha stuff out of it, please. If your game is good, people will come back to it. Forcing them out of obligation to shape their lives around it will just cause them to burn out and never return.
Ofc my only gripe is that the rewards are timed exclusives. If you can get them whenever, I wouldn't see a problem with it.