I am remodelling a few pages on an established site, but on checking the Inspector there are over a couple of hundred page errors. These seem to be triggered by the presence of media content (via Joe’s stack and HTML5 Audio), and resources (webfonts) being available to the site’s manifest.json file. All Greek to me, and the AI explanation feature doesn't help, and of course that file does not seem to exist anyway. Does any of this matter, or is it an over-fussy browser thing (Chrome, in this case)?
https://sandbox.chestermysteryplays.com/discover/history/2013_production/