Legacy System Incompatability with further versions of Mac

Apple have advised that AVG 'legacy system' will be incompatible with future versions of IOS
Advice please.

Hi John,

In light of the current circumstances concerning Covid-19 outbreak, there was a delay. Hope you're well.  
Apple released update 10.15.4 of Catalina to mac OS x users on 24.3.2020. This update contains a check of functionality of kernel extensions.
Catalina would be the last macOS that fully support legacy system extensions. System extensions are a category of software that works in the background to extend the functionality of your Mac.
We’re aware of this situation and working on improvements. Currently, you'll be able to still use AVG program on your existing OS.
Thank you for your understanding in advance!