I think the fault here is at Cachy OS for shipping experimental and advanced stuff as if it is ready for most users.
When I installed it recently on an old machine I purposefully stayed away from these fancy options and chose EXT4 + Grub. I admit having some bad memories about casually using btrfs also made my choice easy. No, most users don’t want to have to baby sit their file system.
Anyway, what even is the point of a system restore functionality if it hasn’t been thoroughly battle tested? They should have been behind an “ADVANCED/EXPERIMENTAL” disclaimer or something until it is very hard to break (including brtrfs not borking itself) and actually rescues users from a bad time rather than creating more problems.
They are unstable from a software compatibility perspective where every updates has a worrying chance of breaking compatibility with old “stale” software (software not managed/distributed by the distro itself), but that does not necessarily means unstable from a system stability perspective. If there was some kind of “system stability” scale for distros i would judge archlinux somewhere in the middle. And, with the nature of how linux development is you might actually get better system stability due to it having fresher software that better supports your hardware. That’s the main reason to try and be a the bleeding edge of desktop linux, sometimes you only get a few shallow cuts and stuff actually functions better.
Any serious breakage such as an unbootable or unusable system is supposedly very rare and only affects a minor portion of the users, with any change going through a long process that hopefully catches it before any harm is done. I do realize the irony of building a system restore functionality for precisely this case and me pushing against it. Again, I just think it should be made nearly bulletproof before it’s pushed into the users.
I’ve been using Arch for nearly 20 years and noted that things are a hell of a lot more stable than it used to be. It’s also hard to excuse it since it has grown and matured so much, it’s not a niche distro nobody knows anymore, even SteamOS is now based on it (though the immutability gives it a huge edge and essentially eliminates the aforementioned issue without relying on the, well meaning, but probably flawed system restore thingy).
Anyway, in my judgement, CachyOS being a downstream distro with a lot less manpower behind it should be quite a bit more careful when introducing such fundamental changes. I can’t say how bad it is affecting their user, it’s up to then to know that and if so hopefully change the defaults or at least better educate the user of the experimental nature of it.