There was a deletion request for that package, because it is not intended for x86 and mirrors a package in the official repos. It seems like it was deleted. I remember it getting an update not to long ago.
You can still clone the aur repo and get the PKGBUILD from there: https://aur.archlinux.org/glibc-widevine.git But be aware, that it doesn’t get updates anymore.
Every package gets updated, when there is an update for it. Dependencies don’t matter for that.
Only if a package depends on a specific version of another package, is there a difference. When the dependency would get updated to a version that doesn’t satisfy the version requirement. Then an error gets thrown and nothing gets updated.
But the package maintainers for the official repos don’t really let that happen. It’s more of a problem with aur packages.
Do you have more than one sound card? Press F6 in alsamixer. I’ve had problems with that before. Although it’s likely not the issue.
When looking at the ASUS list on the Archwiki, your specific model is not listed but a few other zenbooks have problems with the sound. It could help to turn off fast boot in UEFI if you’re dual booting and take a look at alsamixer: https://forums.linuxmint.com/viewtopic.php?t=91453
Linux Mint, until I made a mistake during a version upgrade and aptitude had a memory leak while trying to escape dependency hell and roll every package back. Then I replaced it with arch and am happy to be on a rolling release distro.
You can also tell reflector to ignore certain mirrors in the configuration.