[demo@Manjaro ~]$ yay
:: Synchronizing package databases...
core is up to date
extra is up to date
multilib is up to date
:: Searching AUR for updates...
:: Searching databases for updates...
Packages not in AUR: linux64 linux64-acpi_call linux64-headers linux64-virtualbox-host-modules
there is nothing to do
In addition to what @Olli said, those are packages that are no longer in the repos and are not (or no longer) in the AUR. Therefore, they should be removed, after first installing a properly maintained kernel, of course, because if 6.4 is the kernel you’re currently running, then you cannot remove it — you cannot remove the running kernel…