Why does rsync -a generate a lot of network traffic?

Question

Data synchronization

The catalog with pictures and small files is synchronized daily from one server to another

rsync -av --delete --stats [email protected]$SERVER:$DIRECTORY/ /backup/$SERVER/files/$DIRECTORY/

total volume ~ 30GB, files ~ 700,000.
Today we received a letter from the cloud provider about the transfer of network traffic in volume. I looked at the log for about ~ 30GB consumption every day, but in reality such data was not transmitted.
Below are the statistics for 1 day of rsync operation:

Number of files: 700,763 (reg: 695,702, dir: 5,059, link: 2)
Number of created files: 42 (reg: 40, link: 2)
Number of regular files transferred: 48
Total file size: 30,166,201,400 bytes
Total transferred file size : 102,527,227 bytes the
Literal data: 1,558,104 bytes
Matched data: 100,969,123 bytes the
File list size bed: 9,612,122 the
File list generation time: 0.001 seconds the
File list transfer time: 0.000 seconds
of Total bytes sent: 95.373 of
Total bytes the Received: 12,459,423
sent 95.373 bytes the Received 12,459,423 bytes 35,717.77 bytes /sec
total size is 30,166,201,400 speedup is 2,402.76

Why such traffic?

Answer 1

The solution was an incorrect time zone on the server and an error in the scheduler configuration