I used to see an indication of new forum posts on the Forums page for our group. This one:

https://app.thestorygraph.com/book_clubs/a61251cd-ba25-4ec1-afa7-0b802d7009e5/forums/a2a91ed1-86ea-4c3b-8dca-4c6a95dce27b

for example had a new post added half an hour ago as of when I'm writing this. I only knew that when I went to the Forum page for the group because I remembered the earlier comment count. In the past (a month or more ago, I think) there would have been a red dot next to the forum and then next to the new post. I depended on those (in the absence of notifications) to keep up with group activity.

I'm using a Chromium-based browser (Vivaldi) plus the iOS and iPadOS apps and am not seeing these indicators in any of them.