If you’re using a Mac running MacOS Catalina 10.15.4 or later (including Big Sur), you might have seen a new and somewhat cryptic message pop up when your Mac is turned on, or when you use certain apps.

Titled “Legacy System Extension”, the message goes on to note that “existing software on your system loaded a legacy system extension by (developer) which will be incompatible with a future version of macOS” and while that might not mean much to most people, it is something you should take note of.

So, what exactly does this message mean? Not a lot…