I can't send a message. the color of the icon is now orange, not green

Hi, I’m having a trouble with sending a message from my tablet. I suddenly got unable to send a message ( can’t use Chat GPT ). Just a few minutes ago, I used it wiout any problems. The color of the icon has turned to orange from the ususal green. Fortunately, I can log in and use it from my iphone. But how can I handle with this tablet thing?