Why does my iMac desktop keep asking to double press the power button for Touch ID keyboard connection?

see if there is anything additional here—

If your Mac asks you to allow an accessory to connect

Magic Keyboard with Touch ID

Set up your Magic Keyboard, Magic Mouse, or Magic Trackpad with your Mac - Apple Support

A SafeBoot Start up your Mac in safe mode - Apple Support will sort many anomalies

Does a quick disk repair before it fully boots up, and certain system caches get cleared and rebuilt, third party system modifications and system accelerations are disabled temporarily.

Login and test. Reboot  as normal and test.  Caches get rebuilt automatically.

This test will tell you if third party interference; most extensions etc are not loaded in safe boot mode. 

Call Customer Support  (800) MY–APPLE (800–692–7753)

or on line  https://getsupport.apple.com/

or call  AppleCare Support at 1-800-APLCARE (800-275-2273)

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

Contact Apple Support - Apple Support 

To be proactive you can file a bug report / submit your Apple Feedback here:  Product Feedback - Apple

alyork2 wrote:

I have toggled Bluetooth. Updated and restarted the desktop. Disconnected and reconnected the keyboard numerous times. I keep returning to double press the power button to assure a connection and I do, but my answer is try again.

[Re-Titled by Moderator]

See if there is anything here—

If Touch ID isn't working on Mac

Verify your software is up to date…

The current stable release of Sequoia including bug fixes, security updates is macOS 15.3.2

Keep your Mac up to date - Apple Support

Keep your Mac up to date - Apple Support