error when starting a study (TypeError: my_next_card() got multiple values for argument '_old')

[j0yyyyy]

the addon seems to work at first, the options shows up in the tools bar and it seems to work when I recalc, but when I try to study my deck I get this error message:

Debug info:
Anki 2.1.66 (70506aeb) Python 3.9.15 Qt 6.5.2 PyQt 6.5.2
Platform: Windows-10-10.0.19045
Flags: frz=True ao=True sv=3
Add-ons, last update check: 2023-10-01 12:07:56

Caught exception:
Traceback (most recent call last):
File "aqt.webview", line 46, in cmd
File "aqt.webview", line 153, in _onCmd
File "aqt.webview", line 665, in _onBridgeCmd
File "aqt.overview", line 92, in _linkHandler
File "aqt.main", line 713, in moveToState
File "aqt.main", line 734, in _reviewState
File "aqt.reviewer", line 166, in show
File "aqt.reviewer", line 186, in refresh_if_needed
File "decorator", line 232, in fun
File "anki.hooks", line 89, in decorator_wrapper
File "anki.hooks", line 86, in repl
TypeError: my_next_card() got multiple values for argument '_old'

it doesn't specify which addon causes it, but it only happens when I enable morphman, and doesn't anymore when I disable it.