Apple recently released the second release candidates for iPadOS 15.6 and iOS 15.6 to developers.

The second release candidates for both softwares are 20F66, which replaces the first RC build, 20F65. RCs are typically the last beta versions before a public update is released. It’s expected that this will happen in the following week or so. As far as changes are concerned, there seems to be no notable addition except for the News app having a Sports tab, as well as a Siri prompt for screen recording.
Developers can access the RC beta versions by updating their devices via the Apple Developer Center and joining the beta test program. Public beta versions are available to download in the Apple Beta Software Program.
Users are not advised to install beta updates on their primary devices as it could lead to bugs and performance issues that can cause loss of data.