https://wccftech.com/apple-seeds-ios-14-ipados-14-beta-4-and-macos-big-sur-first-beta-to-public-beta-testers/

Today, Apple has seen fit to release the iOS 14, iPadOS 14 beta 4 and the first beta of macOS Big Sur to the public for testing purposes. If you're part of the public beta program, you can download the latest beta right now on your compatible iPhone, iPad, and Macs.

For iOS 14, users who are currently running the third beta can update to the latest build via over the air mechanism. However, make sure that you have installed a proper configuration profile from Apple's public beta website. Take note that you should not install the iOS 14 beta builds on your primary device as it is crawling with bugs at this point.