Sorry for the inconvenience. This was a global quality assurance edit, identical for about 120,000 POIs: “site_type=” has been removed where there was a “archaeological_site=” tag with the same value. To track the changes, you can find the documentation here (step 2): 
https://wiki.openstreetmap.org/wiki/Automated_edits/ChillyDL#site_type_to_archaeological_site_implementation
