Missing photo album after iOS 26 update and iCloud sync

I have one of my photo album disappeared after the update to iOS 26 and the backup/sync with iCloud. I did both the update and sync recently, so I do not know what caused it. It seems I have my other albums staying fine, and no photos deleted as far as I know. Can anyone tell me how to recover this album as it will cause a lot of effort to recreate the album again. Thank you.

[Re-Titled by Moderator]

Original Title: photo album diappeared