iPadOS 26.3 wiped out photos in folders

Are the photos that appear to be missing from your Albums also missing from the full Photo Library? The Photo Library is accessed at top-left of the Photo App sidebar.

Your Albums are simply a collection (sub-set) of photos within your main Photo Library - and are effectively links to the actual photos. In some circumstances, and while rare, the links within the Album can be corrupted - while the actual photos remain accessible from the Library itself. If this should occur, simply delete and recreate the Album.

Deleting an Album does not delete the actual photos from the Photo Library.

You're very welcome. I'm delighted that none of your pictures have been lost - and that the problem has been successfully resolved.