
I have a SPO List where i have a custom form. In the list is a People Picker Column. If I use the default form everything works like it should just does not look good. I create a Form with PowerApps and the people picker display i:0#.f|membership\\|Useremailaddress instead of Displayname. Once selected when you go back to the List it show correctly there.
Right now the DisplayFields and SearchFields properties of your People Picker DataCardValue is most likely set to ["Claims"] as shown here. Change them both to DisplayName by going to Advanced of the Combo Box for the People Picker. After doing so you will see the Display Name. You can also change those properties to show the email address by placing Email in those property fields.