It definitely is right on schedule for bunny puberty. I had a foster pair of females who started a little chasing and humping. The were able to stay toether because it didn’t escalate, but it is important to keep a close eye on this as they can really do damage if fighting occurs.
Keep a watch for any triggers also. It may be when you are approaching with food for example. Or there may be items they are becoming possessive about. Like a hidey box or litter box.
Is the hair being pulled from the back of neck area? They often bite down on fur there when humping. Or are you seeing tufts being pulled from the hind end?
Earlier this year, one of my female rabbits got into the area of my other M/F pair and the female of the pair latched onto her. She bit down low on the hind end and as the other bunny tried to get free, it caused the skin to tear on the underside. She ended up needing stitches. :/ The vet said that is a common area they go for…