numpy TypeError: can't multiply sequence by non-int of type 'str'

After upgrading from numpy==1.22.2 to numpy==1.26.4 and python==3.9 to python==3.11 start getting errors

splits.sort_index(ascending=False).fillna(Decimal(1)).cumprod().sort_index(ascending=True)File "/venv/lib/python3.11/site-packages/pandas/core/nanops.py", line 1742, in na_accum_func    result = accum_func(vals, axis=0)^^^^^^^^^^^^^^^^^^^^^^^^TypeError: can't multiply sequence by non-int of type 'str'

No idea, where this error comes from