using the power of flex tape, i’ve stuck these two threads together
This bug seems to occur when you click on the “replying to” icon, and the post being replied to isn’t loaded (because it’s too far up). You can see it on this post (like in the screenshot):
But also on any other post that’s replying to a post ~10 posts above it in the thread. Here’s another example:
Google searches didn’t find anything on this, but it seems to have started since the latest forum update.