The images can still be viewed by guests.
For example I uploaded image1, image2, image3 and upload them all to a private album (anyone with link), if I share image1 publicly, once they view it using the viewer, below my username, it shows
Added to Album1 - 12 Hours Ago
and below that
In this album then next to it the image thumbnails that I uploaded on album1. Even though I only shared image1 link, the guest can still view all the images under that album. I also tried to flag image1, image2, image3 as unsafe but still guests can view all of them because the thumbnails are clickable with their own viewer link.
I think it's best not to show the other items under a private (anyone with link) album or maybe a way/setting to hide them.