I remember some discussions that MNE-Python’s notch_filter with method=="spectrum_fit" as a parameter was supposed to be a “cleanline”-like approach.
See also the parameter description from the docstring:
‘spectrum_fit’ will use multi-taper estimation of sinusoidal components. If freqs=None and method=’spectrum_fit’, significant sinusoidal components are detected using an F test, and noted by logging.
However, this method for notch filtering in MNE-Python is probably still suffering from some bugs, see also: MNE Multitaper notch filter consumes a lot of RAM. · Issue #18 · sappelhoff/pyprep · GitHub