
select toDateTime64(-86400 ,9,'UTC') ==  1969-12-31 00:00:00.000000000

select toDateTime64(-86400.00 ,9,'UTC') ==  1970-01-01 00:00:00.000000000 


However, I expect both outputs to be same. 

Version affected : 22.8
ColumnsWithTypeAndName tmp_args;
                if (source_is_nullable)
                    tmp_args = createBlockWithNestedColumns(arguments);
                else
                    tmp_args = arguments;
                const ColumnNullable * nullable_source = nullptr;
                
                if (source_is_nullable)
                {
                    if (arguments.size() != 1)
                        throw Exception("Invalid number of arguments", ErrorCodes::LOGICAL_ERROR);
                    nullable_source = typeid_cast<const ColumnNullable *>(arguments.front().column.get());
                }
                
                auto tmp_res = wrapper(tmp_args, nested_type, nullable_source, input_rows_count);
                
                if (!tmp_res)
                    throw Exception("Couldn't convert " + arguments[0].type->getName() + " to "
                                    + nested_type->getName() + " in " + " prepareRemoveNullable wrapper.", ErrorCodes::LOGICAL_ERROR);
                return wrapInNullable(tmp_res, arguments, nested_type, input_rows_count);
            };
        }
        else if (source_is_nullable)
        {
            
            return [wrapper, skip_not_null_check]
                (ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, const ColumnNullable *, size_t input_rows_count) -> ColumnPtr
            {
                auto tmp_args = createBlockWithNestedColumns(arguments);
                auto nested_type = removeNullable(result_type);