When viewing a photo on the Proton Drive website, there is currently no way to show the photo in its native size. By default the photo is resized to "fit the window", and you only have the option to zoom in (which applies a factor of 1.1) or zoom out (factor of 0.9). You can't set the zoom level at exactly 100%.

This is very annoying, especially for things like screenshots or images of text, which will always be kind of blurry when not shown in their native size.

Maybe the button that displays the current zoom level, which currently resizes the photo to fit the window, could toggle between "Fit to window" and "100%".