BUG: Bug in mask method when handling pd.NA with Int64Dtype

[IceyDuan]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd
from pandas import Series
from pandas.api.extensions import Int64Dtype
series = Series([None, 1, 2, None, 3, 4, None], dtype=Int64Dtype())
result = series.mask(series <= 2, -99)
print(result)

Issue Description

I am encountering an issue with the mask method in pandas when it is used with a Series of type Int64Dtype. Specifically, when trying to mask pd.NA values, they are being replaced, which is not the expected behavior. I expected the pd.NA values to remain unchanged, but they are being incorrectly filled.

Expected Behavior

Series([None, -99, -99, None, 3, 4, None], dtype=Int64Dtype())

Installed Versions

python: 3.11.1
pandas: 2.1.3

[asishm]

Thanks for the report. This is a duplicate of #60729

[rhshadrach]

Agreed @asishm - closing.