In APP server, SM21 check the system log, found a lot of "SAPSYS R6 8 Perform rollback"

https://forums.sdn.sap.com/thread.jspa?threadID=478722

This is normal and you will see it done by sapsys (internal) in your System Log SM21.

An SAP rollback is performed when a user backs out of a transaction losing previously entered data, therefore to maintain transactional consistency SAP does not partly save the data, it performs a rollback.