If this happens (and the association for the files is “Python Editor” as the default in the settings), you can right-click the file and “open with> another” and select “Python Editor” from the list.
This parameter should be saved for this file later (what could happen is that you opened the file as text, and Eclipse is saved, therefore, opening it again using the PyDev editor, you need to establish a connection again).
ps: PyDev, , PyDev ( , ).