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?
{
        ColumnPtr result_column;
        if constexpr (to_decimal)
            result_column = executeInternal<ToDataType>(arguments, result_type, input_rows_count,
                assert_cast<const ToDataType &>(*removeNullable(result_type)).getScale());
        else
        {
            if (isDateTime64<Name, ToDataType>(arguments))
            {
                UInt64 scale = to_datetime64 ? DataTypeDateTime64::default_scale : 0;
                if (arguments.size() > 1)
                    scale = extractToDecimalScale(arguments[1]);
                if (scale == 0)
                    result_column = executeInternal<DataTypeDateTime>(arguments, result_type, input_rows_count);
                else
                {
                    result_column = executeInternal<DataTypeDateTime64>(arguments, result_type, input_rows_count, static_cast<UInt32>(scale));
                }
            }
            else
            {
                result_column = executeInternal<ToDataType>(arguments, result_type, input_rows_count);