Pamac is a swiss army knife - package manager - as it supports a variety of package formats and installations.
- install fetches a package from the official repo
- build creates a custom package using instructions pulled from Arch User Repository (short AUR).
Only the first - the install command - is supported as this installs packages from Manjaro repo.
The results of the build command is unsupported - read below to learn why
When you use pamac to install packages from other sources than the official - those formats are unsupported - snap, flatpak and appimage - as those are designed to be self contained and therefore the system has no say in how they work - any errors or problems must be reported to the developer(s) of the package.