Having trouble with multiple mobile resolutions and my images being stretched/shrunk

Hi all. Wondering if anyone can help. In my game, when the player dies, there is a game over image that pops up from the Canvas.

In many resolutions it looks fine. But sometimes, especially with new phones and their high resolution, it stretches the image greatly. Then in tablet it shrinks the image.

To show more clearly, here is the normal looking game over image (not real for my game, but thought I'd show a pretty square picture for reference):



Here it is with newer phones:



I've tried aspect ratio fitter, I've tried messing with the anchors, but to no avail. Anyone know what I am doing wrong? I just don't get how my buttons still look good with multiple resolutions but the background images don't.

Thank you.

 

Hard to guess without seeing the hierarchy used to build your Canvas elements and what settings are on your background image. I would have thought checking preserve aspect on it would do the trick.