I noticed this around the time 4.4.1 came but but I haven't had a had a chance to post about it. On the main downloads page is this block of text below that appeared around the time of the release of 4.4.1:
On this section of the site you can find software, user guides and release notes for all Cambium Networks equipment.
Cambium provides software updates for products that are within their standard 12 month warranty, and for customers who have enrolled into the Software Maintenance Program.
To purchase a subscription to the Software Maintenance Program please contact your authorized reseller.
So now we need to have a maintenance agreement to get firmware updates? I don’t recall seeing any kind of announcement about this change.