Google has posted a new content policy within its Google Posts help documents that specifically disallows businesses to add phone numbers in the content of their Google Posts. Joy Hawkins posted on Twitter "Google clarifies phone numbers are not allowed in Google My Business posts."
Google Posts show up on your local knowledge panel in Google Search and you can share messages with customers that way. But you can no longer share a message and include your phone number in that Google Post.
This new policy is named Phone Stuffing and Google wrote "To avoid the risk of abuse, we do not allow your post content to include a phone number. You can make your phone number available on your Business Profile or website."
Google said that you should "instead, you can attach a "Call now" button to your post that uses your verified Business Profile phone number." Yes, here is what that feature looks like, it launched back in July 2018.
I am not sure I am a fan of this change but it is what it is...
Forum discussion at Twitter.