A little more details that might help in the future.
celt was removed from the Manjaro repositories in Stable Update - 2022-07-21, and it exists in the AUR.
pacman -Ss celt returns nothing, but pamac search celt shows it in the AUR.
This means if you have the package installed (things change) and there is a higher version in the AUR and you run an AUR helper — whether yay or pamac with the feature enabled, the package will be built from the AUR. One way to prevent this, is to always update your system without any AUR helper, then run pamac list --foreign to display packages which are installed but not in the Manjaro repositories. See additional details.
There’s a link in every Stable Update Announcement in the 1st post/Topic, before the poll, titled, “A list of all package changes can be found here”. The text for removal will look like:
There is one difference in the above Announcement. Ther word “here” is normally a link to Explore snippets · GitLab, but in this Announcment the text is inline.