How do I fix iMessage not delivering after number change on iPhone 12 Pro Max?

I recently changed my number and everything was going fine. A few hours passed and now every time I text a new person to update them with my new number every message I send doesn’t deliver as iMessage so i’ll have to send it again but instead it says Text Message • RCS. Is there anyway to fix that issue? I tried restarting my phone and turning off my iMessage but nothing seems to work.

[Re-Titled by Moderator]

Original Title: All messages are green coming up green