Edison Williams answered it best “autosomal DNA that stops appearing as a potential connection after eight relationships degrees: 6g-grandparents or 3rd cousins (each represents a distance of eight birth events to you).” https://www.wikitree.com/g2g/569106/why-am-i-on-some-dna-connections-%26-not-on-others-in-my-tree?show=569106#q569106