Hi Rokker84,
Welcome to Microsoft Community.
Image Creator outputs images in square mode by default and there is no option to adjust the aspect ratio at this stage.
Is the situation the same in another brand new or someone else's (not including a Copilot Pro subscription) Microsoft account?
How to create a new Microsoft account - Microsoft Support
If Image Creator's graphics output mode is affected by Microsoft accounts as well as Copilot Pro subscriptions, this may be a situation worth submitting to the product team for further investigation.
You may submit feedback in the Microsoft Edge browser as well. Open the page in the Microsoft Edge browser, then use the shortcut keys "Alt" + "Shift" + "I" to open the feedback window or select the 3 dots in the top right, select Help and feedback, then choose Send feedback (Note that the feedback window will capture the current screen and URL link and email address, and you can add Attachment and record your problem), enter your problem, and click "Send".
If I misunderstand your situation, feel free to correct me and share the information.
Best Regards,
Kyo - MSFT | Microsoft Community Technical Support