DatePipe is not working correctly in Angular 6

If you got a field with format Date from firebase you have to convert it with toDate() before your pipe for example:

{{paciente.data_nascimento.toDate() | date: 'dd/MM/yyyy'}}

You are passing the wrong type of argument. The Date filter accepts Date objects, numbers (number of milliseconds since epoch) and string (see documentation).

I'm not sure what the Timestamp type is, but it looks like it has a seconds property.

Try to get the number of milliseconds since epoch from that object

{{(paciente.data_nascimento.seconds * 1000) | date}}

Or there might be a built in method to get it

Edit Apparently, since you are using Firebase, you can call the built-in toDate method to convert the Firebase object to a plain JS Date object

{{paciente.data_nascimento.toDate() | date}}