New Macs keep asking about old discarded Mac credentials
Could it be that you forgot to sign out of iCloud on the 2019 MacBook Pro from your former job?
When setting up a new device, if iCloud Keychain is active, you will be asked to type the login password or passcode of another device that you are signed in to with your Apple ID, see Approve a device to use iCloud Keychain for details.
If you forgot to sign out of iCloud on one of your devices and have given the device away, it could happen that Apple asks you to type the password of that device. In this case, you will have to manually remove the device, as explained in this support article: https://support.apple.com/en-us/HT205064. For example, using the Apple ID website:

Sign in to your Apple ID account page (https://appleid.apple.com), then scroll to Devices.

Click the device to see its details, then click &quot;Remove from account.&quot;


Review the message that appears.

Click again to confirm that you want to remove the device.


For more information on how Apple designs security, see the Apple Platform Security website.