https://wccftech.com/apple-seeds-third-beta-of-ios-13-6-macos-10-15-6-watchos-6-2-8-tvos-13-4-8-to-developers/

Today, Apple has seen fit to release beta 3 of iOS 13.6 macOS 10.15.6, watchOS 6.2.8, and tvOS 13.4.8 to developers for testing purposes. The third beta builds arrive three weeks after Apple saw fit to release the second beta. If you're a developer, you can download and install the latest build on your compatible devices right now. If you're not part of Apple's beta testing program, head over to Apple's Developer website to enroll.

Here's how you can install beta 3 of the following updates on your compatible Apple devices.