This can happen and it's usually solved by just introducing a new package which is the old version of the package, and which won't be updated.

But this isn't really the aim of Arch. I've never had this issue except for with Spotify when installed via pacman, and then only needed it to get playback of local music files.

After I switched to installing it from Flatpak, it included all the necessary packages with correct versions (obviously, because that's how Flatpak works).

But as I said, the aim of Arch is to support working, latest versions of software. If you want to be able to roll back stuff, Arch is probably not for you, even if it's very simple to roll back stuff if you have the package file on disk or it's still available in the remote package repo. But if this is something you often come across, sure.