Bad form by the player. Taking tackling out of the practice isn't going to help players be more safe. Practicing how to tackle correctly will reduce injuries..
Head is down but eyes are up slightly, got his head on the correct side of the runner but did not wrap and drive the legs, he launched himself. He got there with aggression and aimed for the outside thigh but without wrapping a big RB can bounce off that and keep going or dodge and make you look stupid. I would make our kids do it again if I saw that technique.
If he gets the head up more, aims for the same side, wraps his arms and runs "through the tackle" not "to the tackle" he would have been in a much more reliable and more safe tackling position.
Coaching youth football is hard now. Because kids are encouraged to start later and they have limited the contact soo much that you can't teach the kids the proper form. They just don't get enough reps and aren't allowed to work thru their fear. Some kids use bad technique that get them hurt because, they fear the contact and go into tackles in a bad position. You can't talk them out of being afraid to hit or being hit.. they have to work their own way thru it.
I like these robot dummies if they will actually use them to teach good technique and actually let coaches work on tackling more than a day a week.