Reaching out to anyone else having similar problems to me. I've got a S9, Galaxy Buds and Garmin Vivoactive 4 Music.
Playing music from the S9 to the Buds is usually fine; the S9 is in a waist band so stays roughly a fixed position away from the Buds. If they phone is in a pocket though the playback can sound slurred intermittently. Wearing the GV4 on my left wrist creates this slurred play back everytime. I'm not sure if it's the GV4 or the Buds causing the issue but if anyone else has had this problem i'd be interetsed to hear how you fixed it.