Thank you for reaching out. I have tried to open the screenshot on both windows and mac, and I am not able to see any color difference in the preview and saved file. I'd like to confirm if you're on the latest version of XD. Also, could you please share the file with me over a private message so that I can check at my end?
To send a private message, click my profile picture and use the Message button and please send the URL of this forum post for reference.