My texts are green when texting another Iphone

I recently got a new phone I was an android user and I finally got an iPhone the first thing I did on it was text my friend and I sent her a gamepigeon because we’ve always wanted to do that but instead it sent as an image which was really weird and then my texts were green my texts are green with everyone iPhone user I text when I got my new phone I transferred my number over from my android(galaxy s9) could that be the problem I am on a iPhone 15 pro max and have been updated to latest ios