Perhaps you’re thinking of when the Costume event went on a “hiatus” after the initial launch in November, until January, and returned with updates to the Portal — but no new Costumes.
The changes were primarily a chance at the current HOTM, getting both the Hero and Costume together, adding in Featured Costumes, adding a Bonus Chest, and increased cost for Summons. Details here: 🧪 Early Information on Costumes Post-Hiatus Updates [Part of The Beta Beat v26]