The technical/functional reason why back button doesn't redirect to home screen from performance doc

Summary

Customer is requesting to know why after viewing performance document and clicking the back button it does not redirect to home

Content

Customer states that when the manager receives an approval notification email > they open it > click the link to be directed to the performance document > view the document > click the back button and it redirects them to the performance page under career and performance. They do not think this is correct. They think clicking the back button in the UI should redirect them all the way back to the home screen. I advised this is correct and per design, but they do not understand why this is per design and want to know the logical technical and