This is a new data type from Amazon Ads (currently in BETA phase). https://advertising.amazon.com/solutions/products/amazon-attribution?tag=googhydr-20&hvadid=485416008843&hvpos=&hvexid=&hvnetw=g&hvrand=2206124823369762344&hvpone=&hvptwo=&hvqmt=b&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1005424&hvtargid=kwd-976218218284&ref=pd_sl_6fdsfc5665_b_sspa_ggl_d_es_ct_485416008843.