You sure it wasn’t another user? I don’t remember discussing RT kernels.
Changing kernels is not the issue.
The problem with Arch Linux and Arch-based distros, such as Manjaro, is that a minor kernel update “pulls the rug from underneath your feet”.
Debian, Ubuntu, Mint, etc, handle this properly by using a meta package for a major kernel version, with separate packages for each minor kernel version. No interruption in workflow before reboots, and no confusing issues, such as this one. Reboots on those distros are not “borderline required” after kernel updates. You can continue to use your system uninterrupted, and reboot at your own leisure. A reboot isn’t simply an inconvenient waste of time: It also breaks workflow and flushes everything from RAM, including cached data. This has a performance penalty.
To manage, prune, and cleanup kernels, etc, is not exclusive to this either, so “size” is dealt with regardless of distro as long as you prune your older kernels manually or automatically.