Just leaving this here in case it helps anyone searching for quarantine issues on macOS.
Remove the quarantine flag on a VST3/AU plugin so you can move it between Macs while testing:
xattr -rd com.apple.quarantine "/Library/Audio/Plug-Ins/Components/MyPlugin.component" // or xattr -rd com.apple.quarantine "/Library/Audio/Plug-Ins/VST3/MyPlugin.vst3"That's if they're in the standard location. If they're somewhere else, like the User folder, adpapt the file path.