sloz when I’ve posted a message I get a dark overlay, and I have to reload the page to remove
I occasionally get that as well!
At least in that case, your post has been saved to the Community, so the only downside is having to refresh your browser.
In the red box scenario you have to also do that and remember to save your post, then paste and attempt posting again.
I see @guy_ow is on shift and may have an insight beyond ours.