If you type and underscore in the name of a function

def public_` # I want def public_ip():

it deletes the current line and returns back at the start of the history.

after I have typed a dot it shows the possible completions but when I digit a capital P it deletes the current line and returns back at the start of the history.

http = urllib3.P # I want http = urllib3.PoolManager()

Note
Actually this is a big problem of bpython-curses also on Linux (I've tested it on my Fedora 32, last version) and indeed it is deprecated, but the crucial point is that the real bpython is running on Linux but not on Windows.