I expect it should work:
```
:) select CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))')

SELECT CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))')

Query id: fb057b45-b72a-4d22-9b38-a3136cdf2465


0 rows in set. Elapsed: 0.002 sec.

Received exception from server (version 22.5.1):
Code: 53. DB::Exception: Received from localhost:9000. DB::Exception: Cast to Object can be performed only from flatten named Tuple, Map or String. Got: Object('json'): While processing CAST(CAST('{"x" : 1}', 'Object(\'json\')'), 'Object(Nullable(\'json\'))'). (TYPE_MISMATCH)
```

@CurtizJ what do you think?
}
        bool skip_not_null_check = false;
        if (from_low_cardinality && from_nested->isNullable() && !to_nested->isNullable())
            
            skip_not_null_check = true;
        auto wrapper = prepareRemoveNullable(from_nested, to_nested, skip_not_null_check);
        if (!from_low_cardinality && !to_low_cardinality)
            return wrapper;
        return [wrapper, from_low_cardinality, to_low_cardinality, skip_not_null_check]
                (ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, const ColumnNullable * nullable_source, size_t input_rows_count) -> ColumnPtr
        {
            ColumnsWithTypeAndName args = {arguments[0]};
            auto & arg = args.front();
            auto res_type = result_type;
            ColumnPtr converted_column;
            ColumnPtr res_indexes;
            
            bool src_converted_to_full_column = false;
            {
                auto tmp_rows_count = input_rows_count;
                if (to_low_cardinality)
                    res_type = to_low_cardinality->getDictionaryType();
                if (from_low_cardinality)
                {
                    const auto * col_low_cardinality = typeid_cast<const ColumnLowCardinality *>(arguments[0].column.get());
                    if (skip_not_null_check && col_low_cardinality->containsNull())
                        throw Exception{"Cannot convert NULL value to non-Nullable type",
                                        ErrorCodes::CANNOT_INSERT_NULL_IN_ORDINARY_COLUMN};
                    arg.column = col_low_cardinality->getDictionary().getNestedColumn();
                    arg.type = from_low_cardinality->getDictionaryType();