Google is some small changes to Google My Business Posts that could affect visibility.
Google Posts Go to the Bottom
A number of people have observed that Google Posts have been moved within knowledge panels, getting shifted down reviews and other business information.
Barry Schwartz gave an example of just how significantly the change demotes Posts within the knowledge panel on Search Engine Roundtable. The first picture shows his Google My Business listing in 2017, with a Google Post directly below the address information:
In the second screenshot, the latest Post is all the way at the bottom, only placed ahead of other search suggestions:
New Post Length Limits
Additionally, it appears Google My Business is changing how it limits the length of Google Posts.
In the past, Google required a minimum of 100 words per post with a maximum of 300 words per post.
Now, the company is changing to limit posts to 1,500 characters, rather than limiting the length based on words. There appears to be no minimum length for Posts.
NEW: GMB Posts now can have 1,500 characters in content length.
— Ben Fisher (@TheSocialDude) September 26, 2018
If anything, the change will make Posts shorter for most businesses, since 1,500 words roughly equate to 250 words. Given, this depends on the length of the specific words a person uses.