All of these models were listed on the US Apple Store as recently as Sunday, MacRumors notes, but by Monday following their links led to a message that "the product you're looking for is no longer available". We can confirm that none of them are available on the UK store either.
What's behind the various changes is unclear at the time of writing, and it could be related to the global component shortage; just as Apple has been reducing iPad production in order to prioritise supplies for the iPhone 13, it could be diverting resources where they are most needed. Alternatively, it could simply be a matter of making room for new models.
For detailed buying advice, check out our guide to the best Beats headphones.