Arch is almost always up to date with the latest stable releases of libraries and Qt making it an ideal base for KDE Plasma which is a fast moving desktop.
are you involved in this project? i have a little bit of a gripe with this approach. unless your idea is to aim this os at enthusiasts instead of the general public, the user should not have to worry about large upgrades that might leave the system in a broken state. this is why debian is always a little behind: making sure a bunch of different components in a million possible different combinations all work well together is hard work and it takes time. i’m not even saying it’s not possible to use a rolling release model and have a user friendly distro (opensuse tumbleweed does it pretty well), but reliability comes before software recency imo.
edit: btw this is why i said i’m unsure making an os is the job of application developers. what’s ideal for the developers might not be ideal for users.
did they release a changelog?