Apple Pay is turned off on your Mac when certain security settings are modified - one root cause (of many?)
Issue is malfunction of Apple Pay on MacBook Pro due to “Apple Pay disabled because security setting on this Mac were modified” error that shows in Setting/Wallet & Apple Pay.
After going through 4 support personnel levels on October 19 the Apple Pay was restored on my MacBook Pro. Fix was to open a temp user/administrator and re-load Apple Pay. Since only 1 user is allowed, it over-writes old settings. Then go back to your main admin and Apple Pay will work. You can then remove the temp user. The root cause of the issue was not diagnosed by Apple. I now know the root cause.
The root cause of this problem is that Time Machine will not complete a backup on a MacBook Pro if the lockscreen time has expired. Changing this setting disables Apple Pay. Since MacOS 14 (I am not certain about 13) you must turn off or greatly extend the lock screen setting for password control on the MacBook in order to run a Time Machine backup of any duration (often an hour, when the lockscreen normal setting is for a few minutes). If the backup does not finish before the lock screen trigger, you get a red exclamation and a note that all files could not be accessed to complete the backup. One otherwise has to sit in front of the computer and work the trackpad to avoid a lockscreen.
After Support working through fixing my Apple Pay, I proceeded to then update my Time Machine backup volume. I changed the lock screen to 2 hours so the backup would run without timing out. After the backup I went to use Apple Pay on the Mac and the error had returned, and Apple Pay was disabled. The ONLY action taken on Settings after my Support session was to modify lockscreen and execute the backup. The above procedure repaired Apple Pay again. This is quite annoying for anyone performing regular TM backups. This bug does not occur on my iMac, only the MBPro.
MacBook Pro 13″, macOS 15.0