#[tonz]As far as I can tell I only updated one plugin this weekend (Postie, which allows me to e-mail updates to my blog), and I think I updated to WP version 5.2.1 before the feed failed. I did tinker with the theme on Friday and Sunday, but cosmetics only, except for a function for CSS that Sempress puts in the html header.
#[tonz]So nothing, except for WP5.2.1. that might obviously impact the generation of the RSS feed. Except that I don’t know which IndieWeb plugins influence the RSS feed, and whether they might not be playing nice with WP5.2.1.