Today, Apple is releasing the third developer betas for iOS 13.4.5, iPadOS 13.4.5, macOS 10.15.5, watchOS 6.2.5, and tvOS 13.4.5. Interestingly though, iOS 13.4.5 and iPadOS 13.4.5 have new versions. They're both version 13.5 now, and there's a good reason for the change.
They now include the new contact tracing API that was announced a few weeks ago, and it can be used by health institutions. Normally, a bug fix update like iOS 13.4.5 would use the iOS 13.4 SDK. But being that there's a new API, that requires a new SDK, so that's where iOS 13.5 comes in.
Other new features in the update include the ability to share songs, albums, and playlists from Apple Music to Facebook and Instagram. That's the only thing that's listed in the release notes.
As for when these updates will be released, expect to see them within the next month. It's also possible that iOS 13.5 might take a bit longer than the rest since it does have this new API, but we're also just over a month away from WWDC, where the company will announce the next major software updates.