Old:
Instead, Google is going to be replacing the Google My Business app with the standard Google Maps app, meaning you won't need to install a separate app to manage your business listing on google, respond to messages, etc.
Related: How you respond to quote requests is changing
(Your Company Name), we’re updating the way you interact with quote requests from your Business Profile to simplify how you connect with potential customers. When you get an email with the quote requests details, you’ll now be able to reply inline to continue the conversation via email or you can call the customer if they provided a phone number.
With this change, messaging is no longer supported to respond to quote requests from the 'Request a quote' button on your profile, but you can still respond to old messages.