WhatsApp is rolling out the 18.104.22.168 beta version for Android testers, this version promises to fix an issue in call quality, which originated recently.
Wabetainfo reports that some users reported facing loose voice connection during WhatsApp calls. The issue occurs during both voice and video calls. Once connected with the receiver, the connection audio starts to distort. While some of the WhatsApp users experienced low-quality video calls.
However, the issue is currently only reported by the beta testers and not for public release.
To remind you, the latest WhatsApp version is part of the ongoing beta testing program for Android devices. Therefore, the latest call quality fix and improvements may take some time to release for WhatsApp stable users.