Found an app I on my phone I don’t recognize!

Hi! This morning I woke up to find a random app I don’t recognize and don’t remember downloading. One really curious thing is that while this app is not included in my purchased apps history, if I search the app manually, it shows the cloud download icon. It was even located near my recently downloaded apps. I deleted this app immediately and changed my AppleID. This is so strange and confusing. Is there anything else I should do? Please help.