You cannot prevent the scanning, but disable some of the memories, if you do not want to see them.
Photos is scanning the photos for faces and objects to make it possible to search for the content of photos. Photos on iOS does not allow the users to tag the photos with titles, descriptions, or keywords. So the only way to search for a certain content like flowers, or beaches, or parrots etc,, is the automatic classification of the photos according to categories.
To prevent the creation of some memories, go to Settings > Photos, then turn off Show Holiday Events. https://help.apple.com/iphone/12/#/iphd4f70e68fhttps://help.apple.com/iphone/12/#/iphd4f70e68f
To prevent the further creation of the same kind of memories you can try to block the memory:
Tap the For You tab, then tap a Memory.
Tap the More Options button, then tap Delete Memory or Block Memory.