See the release notes:

• Web (OpenTok.js) version 2.23.4: https://tokbox.com/developer/sdks/js/release-notes.html
• iOS version 2.23.1: https://tokbox.com/developer/sdks/ios/release-notes.html
• Android version 2.23.1: https://tokbox.com/developer/sdks/android/release-notes.html
• Windows version 2.23.2: https://tokbox.com/developer/sdks/windows/release-notes.html