Python bindings for v5 of Qt Formula was removed
Last version was
pyqt5 requires the following formulae to be installed:
sip 4.19.8_1 Tool to create Python bindings for C and C++ libraries

Recent formula history

Xu Cheng pyqt5 5.8.1
ilovezfs pyqt5: depend on qt@5.7
ilovezfs pyqt5 5.7.1
ilovezfs pyqt5: revision for python3
ilovezfs pyqt5 5.7

Formula code at GitHub