I have been daily driving since 2018 on Manjaro + KDE. In the beginning, considering it is a rolling distro I just update the system every other week and it would break fairly often. But in reality most users really don't need to do sudo pacman -syyu unless they need certain and specific software update. That's the great thing about Linux, it is not forcing you to update like Windows update. You do update when you specifically need it and know what you want. There's barely any serious virus or security exploit for average Linux users. There are many top world supercomputers running on outdated kernels.

If you are not chasing bleeding edge status, and update your Manjaro less regularly, say on par with Linux Mint update schedules of every 6 months or so, then it'll break less often unless you are really really unlucky.