This version is expected to primarily include bug fixes, and may be the last point release for iOS 13.

Having just released iOS and iPadOS 13.4 on March 24, with big new features like trackpad and mouse support for iPads and iCloud folder sharing, Apple is moving on to its next minor release.

For some reason, the company has skipped over iOS 13.4.1 through 13.4.4 and gone right to iOS 13.4.5. That doesn’t mean we won’t see those minor point-releases, only that if we do, we can expect them to be such minor bug or security fixes that Apple would directly release them without an external beta test.
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https://www.macworld.com/article/3535513/ios-ipados-13-4-5-features-release-date-beta-how-to-install.html