why is my ipad telling me to touch ID requier your passcode when ipad restarta

All iPhones and iPads (with Touch ID or Face ID) require you to enter the passcode after a restart. You may also have to enter the passcode if you have used the wrong finger or face multiple times or have not unlocked your iPhone/iPad for some hours.

Apple Support has a great article that covers this. The following points are taken from there.

You might need to enter your passcode or Apple ID instead of using Touch ID in these situations:

• You just restarted your device.
• Your fingerprint isn't recognized five times in a row.
• You haven't unlocked your device in more than 48 hours.
• You just enrolled or deleted fingerprints.
• You're trying to open Touch ID & Passcode in the Settings menu.
• You used Emergency SOS.

Why?

TouchID and FaceID both require a Passcode to be set prior to configuring the biometric authentication. The device Passcode provides a fallback authentication method if biometric authentication methods cannot be used - and is used to enable the Secure Enclave (security chip) of the device.

The passcode, if biometric authentication fails, unlocks the Secure Enclave - and releases the encryption keys that secure your encrypted data.

When your iPad is initially restarted, your biometric data is similarly secured by the Secure Enclave. Your passcode unlocks the biometric data, after which TouchID/FaceID are enabled.

Locking your biometric data provides an additional layer of system security - inhibiting “compelled access” via biometric data. This may be of particular importance in countries where you may be forced by the authorities to use your biometric identifiers - these having less legislative protection than your device Passcode (which may have been “forgotten”). This can have particular relevance when crossing international borders - or if you are unfortunate enough to have your device stolen from you with menace.

If you are interested in this specific aspect of system security - and your rights - you can research it online.

This is normal procedure for Touch ID devices.