Gerard U we identified the root cause and fixed the issue now.

Hi Gerard U, there was a major architecture change on the rendering of the knowledge base site to make it faster and sleek. There are a handful of pages on some of our customer sites that got affected, especially when the customers used custom CSS/JavaScript. We are addressing it on priority. I sincerely apologies for the disruption.

I also noticed you have put a "Smart bar" on the site to highlight this problem to your users. I have taken a quick look and looks like only the release notes articles are affected. Maybe you can restrict the "Smart bar" to only those pages by using the advanced visibility rule URL that contains "releases"