Hey there theoldabattoir,
That is a strange issue to occur, especially if your messages send and are received by the person who received those texts. Let's rule out some possible causes, along with learning more about what's happening:
- When did this start to occur?
- Does this only occur with one contact, or all contacts you send messages to successfully?
- Sometimes unexpected behavior can be resolved with a restart: Restart your iPhone
- We see you have iOS 16 installed, but the latest version is iOS 16.4. You can verify this within Settings > General > About. In case you needed it, this link shows how to first back up, then Update your iPhone or iPad.
- We also recommend checking for a carrier settings update from your carrier: Manually update your carrier settings on your iPhone or iPad
Cheers!