Chrome: 

1. Open Google Chrome
2. Type Google.com 
3. In the search field, type any word, eg: "Test" and click on space
VoiceOver, just says the letter "T", "e", "s", "t" and reads space when I click on space and doesn't say the word "Test"

Now, open Docs, Slides, Sheets on Chrome and when I type any text, VoiceOver doesn't read the word but just letters.

Safari:

  Follow the above steps 2 to 3 in Safari and VoiceOver reads the word

This is possibly a bug or missing code in our implementation of the AXTextMarker APIs. The first thing I'd do is add some logging to see what TextMarker APIs are being called when finishing a word, and what we return.