Belgian Malinois puppies attacked their mother. Why is this happening ?

Hello my friends. I made this short video when the Malinois puppies were already 70 days old. Problems in Linda's relationship with her children began around the 50th day when the puppies saw their mother and attacked her, biting her and aggressively chasing her. Why this happened is still not clear to me. I consulted with more experienced breeders about this, in their opinion, Belgian Shepherd puppies want to “lay” her on the ground in this way and force her to feed herself with mother's milk!? When most of the puppies had gone to their families and I had only three left, I decided to test the reaction of the puppies to the appearance of their mother again. You can see that my attempt did not end well ... They surrounded her again and began to bite, these bites are quite painful! Of course, I stopped shooting, helped Linda to free herself from these childish "hugs". Write your opinion about it in the comments.
Matriphagy - eating by growing individuals of their mothers, usually occurs at the end of the feeding phase, occurs in spiders.
I used this word in a figurative sense :)
I wish you all peace and goodness!!!
I personally filmed the video, my dog Linda and her puppies are on it, all copyrights are reserved...