I'm using the macOS app, and playing around with hiding albums. When I click "View > Show Hidden Albums" to see my hidden albums, they show as expected, but on albums with white artwork, the hidden icon is invisible, so it's impossible to recognise the album as hidden.

See the attached screenshot. The first three albums are hidden, but the hidden icon is only visible on the third, because it has a non-white background. I'd argue that the hidden icon is only poorly visible in this case too. Perhaps you could make it more obvious?