Yes, I was going to say that I washed my hands of the Mchip stuff literally exactly 12months ago. The last thing I did was speak at TTN conference 2018 then told everyone after I walked off stage.
So I can’t say why the supply has dried up this time, but I can tell you how it works. The distis don’t really hold any stock, they just do back-to-back orders. Catalogues (Mouser, Digikey, RS, Farnell) do hold real stock so they are the best place to search.
Microchip direct is also the first place new stock will appear. When out-of-stock the date you will see is today+12weeks, but in reality they could materialise tomorrow. The system is not transparent.
I doubt its a component supply issue as these volumes are close to nothing for Microchip.
Checking Microchipdirect I see there is a 105 firmware coming. This is 99% likely to be the reason for delays. Transitions were never their strong point, and it really messes up the distis/catalogue order books.
My advice - buy any old RN2483A version you can get you hands on and update the firmware yourself