I believe, the “Introduce Yourselves!” post thread has been locked since the new community platform became operational. As such you may want to unpin it because now anyway no new introduction is possible. Since the topic is at the top apart from the “AppSheet Q&A Category” post, it occupies substantial space at the top of the category. As we can see the category header and other options already take up substantial space as highlighted in yellow below.
Alternatively, you may wish to keep it pinned but unlock it so that new introductions are possible.