Hello there, @RebelBabyCow
Thanks for reaching out to the Roku Community.
We understand your concern regarding using a 4K on your Xbox through your Roku device. To start, I would recommend visiting our support page which provides the best settings on my Roku TV for gaming. It covers a range of issues that could be affecting your ability to use 4K on your Xbox, such as improved performance, usability, and picture quality for optimal gameplay.
I would encourage you to carefully follow each step outlined in the article and test your setup after each adjustment to see if it improves your situation.
I hope this information proves helpful to you. Please let me know if you have any additional questions or concerns.
Regards,
Nimfa