The ML community has been asking the authors of that model to rename their project[2] because they are basically stealing publicity by making it seem like the next version of YOLO, despite its performance being worse than that of YOLOv4.[3]
Roboflow has deflected this in the past by claiming they don't know if "YOLOv5" is the correct name[4], but by continuing to promote it, they are directly supporting it. In fact, I wouldn't be surprised that their claim of not being affiliated with Ultralytics to be either false or a half truth, given that all the top pages about "YOLOv5" were done by roboflow, including the first official announcement.[5]
[1] https://github.com/AlexeyAB/darknet/issues/5920
[2] https://github.com/ultralytics/yolov5/issues/2
[3] https://github.com/AlexeyAB/darknet/issues/5920#issuecomment...