Mac Stuido do not respond to an USB apple Keyboard t

If the Mac Studio is on macOS Monterey and your Mouse is working, go to Apple > System Preferences > Keyboard > Keyboard tab and select Change Keyboard Type.

If the Mac Studio is on Ventura, then the Keyboard Assistant should automatically open.

see > Specify a keyboard type on Mac - Apple Support

I would also try a different (Generic or PC) USB keyboard to see if it is recognized.

If that doesn't work contact Apple Support, at > Official Apple Support

Plus you can send Feedback to Apple by

using > Feedback - Mac Studio - Apple

and > Feedback - macOS - Apple

I prepared as follows: you have to un-assign the keyboard from the old Mini.

That is done (if I remember correctly) in the Bluetooth menu (in Monterey on the top) and right click the panel.

Go to Bluetooth settings. It shows - in the Mini - the keyboard.

Select disengage. [It now wont work on the Mini anymore]

Presto.

Then the keyboard is not dedicated to a computer. And it will show up on the Studio in that same menu, where you click: search for appliances nearby.

Select it.

Then the keyboard is known to and dedicated to the new Studio computer.

I my case it was easy - I have one with a cord. The computer then knows what is happening and will assign it immediately/faster at least.