When pressing enter with the cursor like this:

def test():
    print("test")
[cursor]

Emacs (26.1) correctly just inserts a blank line. However, with this:

def test():
    if True:
          print("test")
[cursor]

Emacs inserts a blank line and indents it one level. With this:

def test():
    if True:
        if False:
              print("test")
[cursor]

it inserts a blank line and indents it two levels, etc. Moreover, with two
methods like this:

def test1():
    if True:
          print("test")

[cursor]def test2():
    if True:
          print("test")

pressing enter will also indent the def block, instead of just inserting
the empty line.