At this point so many different people have reused "YOLOv{n}" that the lineage is broken. I don't know how or why it happened, but it continues to be a thing.
I assume this happened because Joseph Redmon, the creator of v1 - v3, left the field of computer vision [1]. So then other people just took (stole?) the name.
At the very least v4 has a paper attached to it. The authors of v5 have claimed that they'll release a paper at some point, but it has never materialized. It doesn't seem like v6 even makes that promise.
[1]. https://syncedreview.com/2020/02/24/yolo-creator-says-he-sto...