Ok so looks like for me it was the site rule with 2 or more links it goes to moderation.
This is not to say other issue can cause it, but this is my issue.
So now need to make sure user understand that, or they get notice of reply or topic requires approval.
So the issue with topic going into pending, is that the topic or reply most likely has invalid formatted code. Example: User type is a URL and hit submit, it is gone. Well, no, it is pending. because https://domain.com/something
is not allowed. And the app does tell the user of the error.
Just glanced at this one, think I have a solution if you have not found one.
So maybe long in coming, but just started working on a new bbpress BuddyPress forum.
Basically if a topic contains an invalid code such as a url (not and image url link), once submit it goes into draft mode. There maybe other reasons, but invalid code in topic is one.
I am currently working on a fix, short of making the tag available global. Biggest issue is link spamming.