What is the actual footprint of the mysql database?

the leased mysql database of Tencent Cloud has more and more data every day, and almost no deletion has been done.
Tencent Cloud displays about 1200 gigabytes, but I use the following sql statement to query the size of each table. With the index, it is only about 600g. (only 3 GB for binlog)

select table_schema, sum(data_length+index_length)/1024/1024 as total_mb, sum(data_length)/1024/1024 as data_mb, sum(index_length)/1024/1024 as index_mb, count(*) as tables, curdate() as today from information_schema.tables group by table_schema order by 2 desc 

what does half the capacity do? Is there an optimization plan? Or is there something missing in my calculation?

Jun.13,2022
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b3b72f-2ba10.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b3b72f-2ba10.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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