No. A chroot still has you running the system that you booted from, but within the session of the chroot environment, the system thinks that its system drive is the one you’ve chroot’ed into. This enables you to use the package manager on the installed drive as if you were running natively off that system. It will also recognize the user accounts on the installed system when it comes to file ownership and permissions.
Certain things will however not work because they operate at a deeper level and therefore still have a reliance on the system you’ve chroot’ed from — e.g. things which require polling the running kernel, which will of course be the kernel of (in this case) the live USB session.
There was a polkit change a short while ago, which caused privilege escalation authentication issues with pamac and other such applications for people running an older kernel. Apparently one needs at a bare minimum a 6.6 LTS kernel, but the advice is to use 6.12 LTS, 6.18 LTS, or a later kernel.
That said, AUR packages should regularly be rebuilt. Some of your AUR packages may also no longer be in the AUR, in which case it is best to remove them.
It is possible that your filesystem got corrupted. Given that your system has — at least, if I’m reading you correctly — never been reinstalled, I presume that you’d still be using ext4 as the filesystem, and ext4 is quite susceptible to corruption from unclean shutdowns. Fixing this would require a repair from a live USB or CD/DVD, but without a chroot — as the matter of fact, the filesystem mustn’t even be mounted.
Another possibility — which would require a chroot — is that your system is in a partial upgrade state due to an interrupted or failed update procedure.
If it was the update that failed, here’s a procedure on how to fix that… 