I found this today and am sharing here, I have updated some of the Discourse forum posts to also include this.

Writefull for Overleaf checks grammar and gives language feedback on the text you write in Overleaf. Using language models trained on millions of journal articles, Writefull corrects grammar, vocabulary, punctuation, and more. Writefull is specifically designed to provide language suggestions for research writing. Writefull for Overleaf is a Chrome extension provided by Writefull, it is not provided or maintained by Overleaf. Both Overleaf and Writefull are part of Digital Science.