Spammers slipping messages into legitimate text threads

First of all, Apple almost certainly has no involvement here.

Secondly, you are likely referring to group messages, not simple one-to-one party messages.

Check the message addressing very carefully. Also note whether they’re green (SMS) or blue (iMessages).

What is the difference between iMessage and SMS/MMS? - Apple Support

What does a dark gray background in text messages mean? I read about the difference in green and blue. My text messages are always green. I have an IPhone XR. After I read this I checked my text and noticed the gray background in one particular message.

I would immediately change your Apple ID password. Settings - name - password and security - change password.

also, I would go to passwords and look at the recommendations and change all of those passwords as well.

had this happen to me and once I changed everything and changed my families Apple ID passwords as well, it stopped. That’s the best thing you can do. To be super secure we even changed our home Wi-Fi network password. That way any avenue they can take to do that is now blocked and the access they had is furthermore removed.

Good luck with that.

Apple has no control over text messaging, that’s cellular carriers.

It’s also an issue on Android.

if your friend is using Android and some kind of messaging service or app, they are the ones spamming you.

If you mean iMessage, block the sender.