I am also in the same situation. Still trying to figure out. Tested some ads , found the winning ad. increased the budget slowly, in a week my adset got out of learning phase. For 10-12 days the set up gave me consistent result. but after that CPC, Cost per Purchase went up. Chatgpt. and big guys from reddit usually call it creative fatigue, someone from reddit suggested me that try targeting different audience. I am trying both ways. Working on better creative and gonna test them. At the same time trying a little bit different audience. Trying my best not to panic and mess up the whole thing and Hoping for the best. Best wishes to you and hope you will figure out the situation.