What is data-gr-c-s-loaded="true" attribute

I was going through a piece of simple HTML code and I came across this in the body tag. The strange part is although this attribute has been used at many places, but there is not much info available on its functionality or usage (or probably I wasn’t able to find it). It is also automatically generated when I run my code through VS Code live server.
<body data-gr-c-s-loaded attribute="true">...</body>

It looks like it is the grammarly extension that adds that data attribute. Likely use for some internal check (like to verify it has loaded into the page).