As an app developer myself, I understand the complexity of updating software to support a new operating system. But Apple, in particular, has a solid developer support model in place which gives application developers early access to new releases for exactly this purpose.
It appears to me that J2R and Adjust AI are written perhaps using an older framework, as all of the other apps seem to have been updated rather quickly and seem to have a different installer method. I expect it is more difficult, for some reason, to update J2R and Adjust AI. Perhaps they are using a third-party developer. In any case, it seems that testing on Big Sur while in beta did not effectively occur.
Also with J2R and Adjust AI, it appears that future updates for those apps are “free” as it is not listed as part of the annual subscription (yet). Perhaps this is exactly why - because the development/updates on those older frameworks are more complex and take more time.