My guess is that Robin’s post is the last one on the page and the javascript has a fence-post error which led it to create a new page.
Also if I click on the post number next to my post
https://britastro.org/forums/topic/new-website-feedback/page/5#post-609928
it takes me to the top of the next page instead of to the post. It should point to
https://britastro.org/forums/topic/new-website-feedback/page/4#post-609928
Robin