Unable to directly Edit html in the browser in SharePoint Online

From yesterday onwards, am Unable to directly Edit html in the browser in SharePoint Online env. i have created a folder called htmfiles in my siteassets librray on my SPO site, and i have a html file that has css, js, and html content.

When i tried to edit the html file, am getting a message, " its just a preview".

Did MSFF make any changes in this behavior for the last few days?