How to get an unencrypted iTunes backup
If you're on latest Mac OS (greater than 10.15 - Catalina) you can perform an iTunes backup directly from Finder
If you get a warning about encrypted iTunes backup (ChatStorage.sqlite) you need to make sure to perform a brand-new iTunes backup by NOT ticking "Encrypt iPhone backup" then extract ChatStorage.sqlite again.
If the "Encrypt iPhone backup" flag is greyed out it means you have some sort of corporate account configured on your iPhone. If so, please delete all those accounts (like Exchange, VPN, etc).