Updating failed. meta value

Trying to change Page Layout from default to normal. Receive the error (in pink bar) of “Updating failed: Could not update the meta value of _kad_post_transparent in database.”

A search for information turns up something to do with the new block editor. (Not verified.) Installed classic editor, but am really rusty with it. Not able to adjust the site using it. ??

Need help in getting functionality back in the site. It worked just a couple of days ago. Updates happened, and now ……….

The page I need help with: [log in to see the link]