iMessage & GamePigeon trouble

Hi, so my younger sister has an iPhone XR and she recently came to me because she’s having issues with both iMessage and GamePigeon. With iMessage as we all know the bubbles are blue when we text another iPhone user and green when texting android. But her bubbles have now just stayed at green even when texting an iPhone? I’ve tried turning on and off her iMessage but nothing seems to work to fix that. And with GamePigeon I don’t know if the problem may be connected with the iMessage problem but whenever she tries to send me a game to play her against it actually sends as an image and not the game. I don’t know how to fix that either and I’d really appreciate the help and fixing my sisters phone. Thank you!