showing error

plugin is working file but showing warning when enable debug mode

Notice: Function register_rest_route was called incorrectly. The REST API route definition for PNFPBpush/v1/subscriptiontoken is missing the required permission_callback argument. For REST API routes that are intended to be public, use __return_true as the permission callback. Please see Debugging in WordPress for more information. (This message was added in version 5.5.0.) in /home/u992033758/domains/localhost/public_html/wp-includes/functions.php on line 5831