I think I’ve encountered this before with students using Windows. I am Mac-centric myself but keep a Windows system just for troubleshooting when issues like this pop up. It happens on my own Windows system too so hopefully my suggestion will work for you.
Change the file extension from .tiff (with two effs) to .tif (with one eff).
I don’t know why this works, and some folks have said that the double-f tiff spelling works fine for them, but it did solve the issue for me and my students who encountered it as well.
Another possibility, not specific to Windows, could be active alpha-channels that can be deleted. If using Photoshop look in the channels pallete. Not sure if this is relevant to the Paint app in your screenshot.
Keith