Hello!
We have users on our instance who find it difficult to tell if a post is bookmarked or not as there is only a change in color when the post is bookmarked.
We think that having an "outlined" version of the bookmark icon (which does not exist in Discourse, according to the Styleguide plugin) when the post is not bookmarked could improve the situation.
Are you interested in a PR that adds the missing icon and replace it in the button ?
Discuss this on our forum.