However, it is important to note if you have deleted the message, then there is no way to download the data. And as a beta tester, you have the opportunity of trying the upcoming features before anyone else and give your feedback to WhatsApp about any bug.
If you're among the users who were annoyed by the faulty timestamps, you can download the latest WhatsApp beta version on your device by visiting Google Play. It seems version 2.18.113 of the Android app supports this feature.
WhatsApp on Android will let users re-download old images and videos that might have been deleted from the user's mobile storage. According to WABetaInfo, the Twitter account that tracks changes in WhatsApp's beta builds, the company is rolling out a new feature for Android that will enable users to again download media files that they may have accidentally deleted. Separately, a WhatsApp beta for Android update (v2.18.111) reportedly added the vCard indexing feature. As WABetaInfo reports, with the introduction of the new feature, it is possible for users to retrieve old media content again even if it has been deleted from their phone. The new feature is now limited to Android version 2.18.113 and is expected to be rolled out to iOS users as well. The undownloaded files were stored on WhatsApp server for 30 days and once it were downloaded, WhatsApp immediately deleted it from its folder. Basically, the WhatsApp servers will store the media files even after downloading them.
In the meantime, you can also download the APK version via the APK Mirror. With the new feature, users will be able to lock the voice recording button instead of holding onto to it as seen in current general builds. It took several trials to download the files deleted 3 months ago. Only if the file has been deleted in sdcard/WhatsApp/ and you have the message in the chat, you can successfully download it again.