Apple has simply stopped selling products from third party brands such as Bose and Sonos.
Bloomberg has done some research both online, but also in physical retail stores to back the claim. Bloomberg states that employees have been instructed to simply remove inventory from third party audio manufactures.
Apple already makes a range of audio products, but with upcoming over-ear headphones expected to be revealed soon, and more smart speaker products expected later this year as well, the change in stock seems to have a degree of credit.
This is not the first time, as Apple is well-known for removing potential competing products before launching their own version.
Bose has confirmed that Apple no longer sells their products, and Ultimate Ears were told that Apple stores would not sell third party speakers come September.