Apple today seeded the first beta of an upcoming macOS 10.15.3 update to developers for testing purposes, one week after releasing the macOS Catalina 10.15.2 update.
The new macOS Catalina beta can be downloaded using the Software Update mechanism in System Preferences after installing the proper software from the Developer Center.
We don’t yet know what improvements the third update to macOS Catalina will bring, but it will likely focus on performance improvements, security updates, and fixes for bugs that weren’t able to be fixed in the macOS Catalina 10.15.2 update.
Read more at MacRumors.com