Legacy system extensions - "Antivirus for Mac"
Recently I did an upgrade on my MacBook Pro 2016, “macOS Catalina” from Version 10.15.3 to Version 10.15.4 and received the following: (What is Bitdefender Planning to do in order to resolve this issue now and in the future, as I was planning a renewal, but may now have to look at alternatives? I would rather not change, I have been using Bitdefender since 2009 on Windows and Mac operating systems.)
Existing software on your system loaded a system extension signed by "DEVELOPER_NAME" which will be incompatible with a future version of macOS Contact the developer for support.
Some system extensions will not be compatible with a future version of macOS.
System extensions are a category of software that works in the background to extend the functionality of your MAC. Some apps install kernel extensions, which are a kind of system extension that works using older methods that aren't as secure or reliable as modern alternatives. Your Mac identifies these as legacy system extensions.
In 2019, Apple informed developers that macOS Catalina will be the last macOS to fully support legacy system extensions, and we've been working with developers to transition their software. By moving beyond these extensions, developers are helping to further modernize the Mac, improve its security and reliability, and enable more user-friendly software distribution methods. A final transition date has not yet been set.
Until the transition is complete, your Mac displays a message when a legacy system extension first loads, and again periodically while the extension remains in use. This give you advance notice that existing software on your system loaded a system extension that will be incompatible with a future version of macOS.”