So it looks like signatures got replaced with a list of posts that reference the post your reading.
Here’s the original post being referenced. Go to the bottom to find all the posts that reference it.
Logged out to check if it was visible to everyone: yes. Checked other posts in other threads to see if it happened to those, too: yes. So this is why signatures are gone.
Also, notice how the references are placed UNDER the reply buttons, whereas your fake signature are placed OVER the reply buttons (since it’s part of the post).