Find my mac is not working on macOs Sequioa

You might try booting the Mac in recovery mode and then run First Aid on the startup drive from Disk Utility. Afterward, disable and reenable the Find My service on the Mac.

This was the fix for me recently with a similar (not exact) isolated Find My issue.

How to repair a Mac storage device with Disk Utility - Apple Support

Repair a storage device in Disk Utility on Mac - Apple Support

❝Note: If you’re checking your startup disk or startup volume, restart your computer in macOS Recovery. See the Apple Support article [...]. Next, select Disk Utility in the macOS Recovery window, then click Continue. If you check your startup volume (Macintosh HD), make sure you also check your data volume (Macintosh HD - Data).❞

Try booting into Safe Mode then restart normally. Sometimes that will fix anomalies.

Start up your Mac in safe mode - Apple Support

There are 4 Categories of Third Party Software / Services that are baffling.

In no special order 

Third Party 2 Way Firewalls 

Commercial VPNs 

Third Party Security Software 

Third Party Disk Cleaners / Optimizer 

If in doubt >>

Download the Application Etrecheck ( External Link ) directly from the Developer.

This is a Diagnostic Tool that makes no changes to the computer.

It makes a coherent and readable inventory of both the Hardware and Software used on the computer 

The application is free or paid for added features. 

The Report will Not Reveal Any Personal Information. 

Post back the Full Report - Share Report >> Copy , then  paste  >>>> using the Additional Text Icon  <<<<

I’m experiencing the same issue. See this discussion on what I tried and some advice given.

Bat Call for suggestions Find My not enab… - Apple Community

I have decided to wait for macOS 15.6 before I try the terminal commands suggested by @zinacef.

FWIW, Find My seems a little flaky. I never bothered using it until you posted. As it turned out, it can locate some of my devices and not others. Plus, different devices find different other devices.