Puppy biting other puppy while playing

My puppy has a puppy friend who she adores, but they both get too excited and bite each other. My puppy is 6 months and about 15 lbs the other puppy is 5 months and about 20lbs, but much taller than my pup. They both bite each others’ faces. There has never been a fight, blood drawn, whimpering, or fear between them. We always separate them once we see a bite. Sometimes they are fine, but we mostly let them play in 30-60 second spurts of chasing each other bc the smaller puppy gets winded faster, then we have them sit and catch their breath until the smaller puppy starts trying to play again. Both dogs have some herding breeds in them so nips and puppy biting have been difficult to train out in general. What is the safest way for them to play and how do you train out the biting? My puppy listens well with redirection in chill environments, but the two dogs ignore all toys when around each other. They just want to wrestle and chase each other