Hello Wexfrod1798,
Welcome, and thank you for posting in Apple Support Communities.
Let’s work together here and find out what’s going on with this one contact and why you are getting the messages.
You didn’t’ mention what iOS version is installed on your iPhone. Do you have the current 14.4 version installed? Go to Settings > General > About, and you can see what’s installed. If you need to update, see Update iPhone, iPad, and iPod touch.
Have you followed the suggestions found in If you can’t send or receive messages on your iPhone, iPad, or iPod touch?
Are you able to send messages to this contact? Is the contact Apple or Android? Asking so we know what we’re working with.
Reach back out with more details, we’ll be here to help.
Have a great day!