I’m happy to report that all Graffix plugins (except for ServerLock, for now) are notarized for use with macOS 10.15 Catalina, Apple’s new all 64-bit OS. This applies only to plugins compiled for Illustrator 2019 and 2020.
In the meantime, here’s a workaround for older versions and — temporarily — for ServerLock. I won’t go so far as to say that I recommend this, but both have worked for me and for other users.
The site Der Flounder explains how to turn off Apple’s quarantine flag using the terminal. A variation on this technique goes like this:
1. Open the Terminal app and run the following command (in this example for ServerLock for CC 2019):
sudo xattr -cr /Applications/Adobe\ Illustrator\ CC\ 2019/Plug-ins.localized/ServerLock.aip
2. Press Enter or Return.
3. Enter your password if asked.
4. Repeat for each plugin.
Illustrator should launch and load the plugins normally.
I sincerely apologize for any inconvenience.