The lack of availability of knives at Spyderco is a fairly recent phenomenon which, I believe, is largely due to demand and supply side issues related to the pandemic.
Add the the fact that they offer so many different knife models and so many variations of many of those models, it's not surprising that it's hard for them to keep everything in production and available at the same time.
Can't say when things will get back to "normal" but the wide number of knives currently "out of stock" at Spyderco is unusual.
If there's a particular knife you want, in my experience, it is unfortunately necessary to check everyday to see if it has become available and then to immediately grab before it goes out of stock again.
A lot of people love the Kapara. It's not my cup of tea but it's back in stock again. Also in stock right now is the SpydieChef which is EXTREMELY popular and I suggest you buy if you don't have one already. It's an easy resell on the Exchange if you end up not liking it.