I would definitely say he is tail biting, if it was snagging it would have tears from the base and if it was a blowout it would have a hole in it and wouldnt be restricted to the end of the tail.
A lot of bettas with heavy tails will do it
The fun thing is that some bettas will do it just because they are bored, if its too heavy, they dont like the tank, and a multitude of other reasons. I swear I had one who did it just to spite me.
Meaty foods, clean and warm water will speed up the tail growth.
Tails grow fast under the right conditions but its different for every betta. It should return to its former glory but you may have a few wonky rays.
Is he in a high traffic area by the way?
Some bettas will become stressed by too much activity outside the tank and tail bite because of that as well.
Heck, he may even be doing it so he can hunt the shrimp better.
Gorgeous betta by the way!