The raid horn sounds multiple times in the middle of a raid wave, around every minute or so. This is inconsistent with Java edition (where it only sounds at the beginning of the wave), and it can be confusing as no additional mobs spawn when the raid horn blares.

To reproduce, trigger a raid (e.g. inflict yourself with Bad Omen and spawn a villager with a bed next to it), and wait without attacking any of the raid mobs.