Did you try the first suggestion to disable PC Speaker in console ?
You can add this command in
/etc/profileor a dedicated file like/etc/profile.d/disable-beep.sh:setterm -blength 0
Most Manjaro users would not need to disable beep in console if it has already been disabled globally
Or
ArchWiki suggestion to remove and blacklist snd_pcsp kernel module is not needed as snd_pcsp is not included in Manajro ISOs
Suggestion to mute mixer control for PC Speaker in ALSA is not relevant for most onboard audio devices (except for some Cirrus Logic and Sigmatel audio devices)
I do not recall any previous forum posts where suggestions for Gnome, KDE or Cinnamon DEs were needed in addition to (or instead of) disabling pcspkr globally
ArchWiki has a lot of information for many use-cases that are not relevant or useful for Manjaro users