The error occurs because the filtered DataFrame still contains a column (i.e., a Pandas Series) that cannot be hashed. Hashing is a process of converting an object into a unique numerical identifier, and it is necessary for identifying duplicates.
To fix this error, you can convert the column that is causing the error into a hashable type, such as a tuple or a string. Alternatively, you can drop the column entirely if it is not necessary for identifying duplicates.
