DBA_DATA_FILES & UNDO Tablespace

Hello Team,

I am running the below query to see whether the change of UNDO Tablespace is reflected or not.

SELECT /*+ no_monitor */ :TS_NAME AS tablespace_name, COUNT(1) AS no_of_data_file, ROUND(SUM(A.Bytes)/(1024*1024*1024),2) AS current_data_file_size_gb

                       ,ROUND(SUM(a.maxbytes)/(1024*1024*1024),2) AS max_data_file_size_gb

 FROM dba_data_files a

WHERE a.tablespace_name = :TS_NAME

AND a.online_status = 'ONLINE'

AND a.status = 'AVAILABLE'

;

But I am getting the below result where total maxbytes are lower than total bytes.

And moreover from EM it is looking like below:

It will be great if you can help me to understand how could this happen.