Texting from iPad Pro to samsung

Are you using Text Forwarding to a linked iPhone?

The iPad cannot send/receive SMS messages without an iPhone. SMS requires a voice cellular service found on iPhones. A cellular plan for an iPad is only a data plan and cannot send SMS messages. Messages over WiFi and Cellular Data works fine when sending to other Apple devices using the Messages app since the cellular service is not needed.

Pam304 wrote:

Just checked. I definitely am

You definitely are using Text Message forwarding on your iPhone?

Forward text messages from your iPhone to other devices - Apple Support

If that is how yours is set up, I would suggest turning off the forwarding, then turn it back on.