Apple is already preparing users for what is coming with macOS Big Sur. Many of the existing applications right now will stop working with the new operating system, which was featured at WWDC 2020. For a security issue, it is intended that certain applications do not run under the new environment in order to provide greater security to users.
Users who have installed the new version macOS Catalina 10.15.4 or later on their Macs, it is more than likely that you have seen a message when using certain applications. The message says something like this:
Legacy System Extension:
Existing software on your system loaded an extension of the legacy system by (developer) that will be incompatible with a future version of macOS.
Legacy system extensions are basically kernel extensions that will no longer work on the Mac soon. They work in the background to extend the functionality of the Mac. Some applications install kernel extensions, which are a type of system extension that work with older methods that are not as secure as modern alternatives. macOS identifies them as legacy system extensions.
The solution is relatively easy. The developer must update their application to accommodate the new macOS Big Sur. Another solution is not to update to this new version of macOS when it is officially released. However, this solution is as they say, "bread for today, hunger for tomorrow", because we will have a Mac with a not so secure and obsolete operating system.
Too bad if the developer doesn't update the app, It is the only option we have left. You have to make sure that the automatic updates of macOS are disabled and wait for the applications to improve and adapt. There is still time, but it is true that you must not be careless.