First, Try and Force restart iPad
Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button and keep it pressed until Apple logo appears, release the button and your iPad will finish booting up.
If the above does not resolve the issue, then, On your iPad, open Settings âž” Messages: Here can you set the Messages function to OFF and then back to ON after a few seconds? This action will have you sign back into the Messages app and then you can determine whether that resolves the issue.
Axel F.