This does not subtract 60 from epoch time but from the address of the variable 'now'...
Maybe this thread can be of assistance how to calculate the time between dates using epoch time:
https://forum.arduino.cc/t/issue-with-0-96-display-code-issue/1195653/12?u=ec2021
The code I shared there can be tested on Wokwi, just follow the link in the thread mentioned above...
Good luck!