I noticed yesterday that I could buy battle pass levels with credits. I had enough credits to buy 15 levels, so I figured I’d hold onto them until I hit level 15 and then clear out the rest up to level 30 with the credits. But today I no longer see the option to buy levels with credits so now I just have a bunch of credits with nothing to spend them on.
Edit: It seems the feature was removed from the shop, but you can still purchase battle pass levels by going into the pass and selecting the consumables option.