iOS: WhatsApp crashing, keyboard stuck, Wi-Fi issues

• VPN's will cause issues with your Network Connectivity even when off. They must be removed to test your connections including those from apps. More and more banking apps will block access to your account when a VPN is installed. Speed Tests have nothing to do with the connectivity issues you will experience on other servers.
• The WhatsApp problem has been noted by others and Meta will need to fix. Deleting and reinstalling is a workaround at this point, and yes you would need to back up your WhatsApp data using their methods, otherwise you Chat History will be lost. Offloading WhatsApp makes no difference, it has to be deleted for a complete reinstall.
• Not sure what you are referring to with your keyboard being stuck, but the issue as you described when starting to type on WhatsApp is not a keyboard problem, it is WhatsApp.
• Beta software is just that. Even though the latest has been designated as a Release Candidate, you can expect the build number to change when shipped. Removing requires wiping your device and restoring from a backup before the beta was installed. There is no support for beta software.

WhatsApp developers acknowledge multiple bugs in their app. They’ve been releasing multiple updates each week and have resolved many issues with their app. Their support team recommends that you delete the current app before downloading and installing the latest version.

Jeff Donald wrote:

...Their support team recommends that you delete the current app before downloading and installing the latest version.

I hope they also say the user must create an iCloud backup in the app settings, otherwise uninstalling will make all messages disappear forever.

Have you wiped the phone and reverted out of Beta? if not then we can't help.

Maybe you have a VPN installed?