You don't even have to use the aur are to have breaking changes. Most recently they changed how vlc was packaged. And broke it causing a lot of problems for users.

That's pretty rare. I ran arch for years and my only issues were from AUR or trying to update extremely out of date machines.

Especially because there is no way to limit the packages installed from a PPA AFAIK. If the PPA has a "new" version of NGINX, or of libc, or of Wayland - you get it, too!!!

Absolutely. Ideally you should have zero PPAs. There’s definitely a cost for using this feature. Most commonly it comes in the form of instability when you end up with incompatible or broken packages because the maintainer wasn’t playing an active enough role. YMMV!

I've run arch for years as well. It happens nearly yearly. I've had updates break completely several times. Partial updates. That required significant manual intervention. Etc Etc Etc. Meanwhile my Debian and fedora systems haven't had a hitch in years.

You can set packages from a particular repo to a lower priority so that they are only installed when you expressly ask for them

How does one do that, Wise Zorro?

I've moved on to gentoo. All the customization and if something breaks I can be sure it's my fault.

I've had updates fail on NixOS. A kernel update didn't generate the initramfs and the system wouldn't boot. Booting to a previous generation and reapplying the update fixed it.

This is very rare, though, and unlike Arch can be fixed without a Live USB.

A kernel update didn't generate the initramfs

This sounds like a bug on Nix configuration, or the kernel build process.

If NixOS had caught the error, you wouldn't have gotten a faulty generation at all. This is different from pacman/apt/dnf, which will happily continue the upgrade, resulting in a broken system with no easy way to fix it.

I haven't installed gentoo in 20 years. I still like arch for it's glaring flaws. And I do like BSDs ports etc. I probably should go through a gentoo install again to see how it changed. Last time I ran it. Was on a first generation Pentium.

Upgrade will upgrade the system to whatever is newest in your package cache. If, for example, you've just performed a partial upgrade and put yourself into an unsupported state, running upgrade without first running update will put your system back in line with itself.

There probably almost never a reason for this, but its the equivalent of running pacman -u which under normal circumstances you will never do

Or the Linux firmware package change that required manual intervention to resolve.

Checks 'automatic updates' box in Discover

On a beefy machine it's nice. Chromium takes forever.

The second y in Syyu is almost always unneeded and just wastes time and bandwidth. Is i remember correctly, it only makes sense when for example you switch mirrors

I think Fedora's COPR carries on the torch, besides Arch's AUR. But generally, yeah, avoid PPA's like the plague. It's been garbage for years now. You'd be better off actually compiling the software yourself.