The digest_logo site setting description and the text below the digest logo option on the logo config page both tell admins not to use an SVG image.
The alternate logo image used at the top of your site’s email summary. Use a wide rectangle image. Don’t use an SVG image. If left blank, the image from the Logo setting will be used.
Because of that, I assumed using SVG images for other logos where this warning wasn’t shown was fine. But then the logo in DiscourseHub didn’t work. In Large icon not rendering in DiscourseHub as site logo - #4 by pmusaraj I learned that an SVG file doesn’t work for the apple_touch_icon setting.
So my suggestion is to update those descriptions to show a similar warning:
Icon used for Apple touch devices. Don’t use an SVG image. A transparent background is not recommended. Will be automatically resized to 180x180. If left blank, {{setting:large_icon}} will be used."
Recommended size is 180 x 180 pixels. Don’t use an SVG image. A transparent background is not recommended.