Spyware
My ex girlfriend installed a few spy tracking apps on my old XR , web watcher , and itrack to name a few , as well she had my apple id password too , when I synced my data to my iPhone 12 pro I believe all the spyware came with it ! I obviously didn't know until after , I have since changed my apple id password and added two factor identification , but I'm not sure exactly what software or what I should do at this point - my phone is still doing the odd things that it did before !
iPhone 12 Pro, iOS 14