MacRumors published a story that Apple has released the third beta of macOS Catalina 10.15.5 update to registered developers.
Apple Seeds Third Beta of Upcoming macOS Catalina 10.15.5 Update to Developers
Apple today seeded the third beta of an upcoming macOS Catalina 10.15.5 update to developers for testing purposes, two weeks after seeding the second beta.
Apple Seeds Third Beta of Upcoming macOS Catalina 10.15.5 Update to Developers