You found the accsee rights of the business user is deleted automatically by Technical User (SAP_SYSTEM).
SAP Business ByDesign All Versions; SAP Hybris Cloud for Customer All Versions
Reproducing the Issue
1. Go to Application and User Management Woc
2. Select Business User View
3. search for the business user and select Edit Access Rights
4. Navigate to Changes Tab
Now, you can find access rights is deleted by Technical User (SAP_SYSTEM) in the change log.
In business configurations, the functionality requiring the removal of all access rights for any user which has run out of validity is marked. When the user became invalid, a background job removed all the access rights of the user.
This is the expected system behavior.
You can verify the issue from:
1. Go to Business Configuration Woc
2. Select Implementation Projects View
3. Highlight the project and select Edit Project Scope
4. Navigate to Questions Built-in Services and Support > System Management > User and Access Management > Group: Remove authorization for invalid users: Do u want to remove substitutions and authorizations for users whose validity date is in the past.
Access Rights , KBA , SRD-CC-IAM , Identity & Access Management , How To