It fails for my reader as well, while slrpnk.net succeeds. I’m not sure what’s going on. RSS isn’t my bailiwick.

$ curl -s https://lemmy.ml/feeds/local.xml | xq 'del(.rss.channel.item)' | gron
json = {};
json.rss = {};
json.rss.channel = {};
json.rss.channel.description = "A community of privacy and FOSS enthusiasts, run by Lemmy’s developers";
json.rss.channel.link = "https://lemmy.ml/";
json.rss.channel.title = "Lemmy - Local";
json.rss["@version"] = "2.0";
json.rss["@xmlns:dc"] = "http://purl.org/dc/elements/1.1/";
json.rss["@xmlns:media"] = "http://search.yahoo.com/mrss/";
$ curl -s https://slrpnk.net/feeds/local.xml | xq 'del(.rss.channel.item)' | gron
json = {};
json.rss = {};
json.rss.channel = {};
json.rss.channel.description = "Solarpunk imagines a world in which today’s existential threat - the climate crisis - is being approached with camaraderie and adaptive ingenuity.";
json.rss.channel.link = "https://slrpnk.net/";
json.rss.channel.title = "SLRPNK - Local";
json.rss["@version"] = "2.0";
json.rss["@xmlns:dc"] = "http://purl.org/dc/elements/1.1/";
json.rss["@xmlns:media"] = "http://search.yahoo.com/mrss/";

$ curl -s https://lemmy.ml/feeds/local.xml | xq '.rss.channel.item | length'
20
$ curl -s https://slrpnk.net/feeds/local.xml | xq -r '.rss.channel.item | length'
20

$ curl -s https://lemmy.ml/feeds/local.xml | xq '.rss.channel.item[1]' | gron
json = {};
json.category = {};
json.category["#text"] = "shitposting";
json.category["@domain"] = "https://lemmy.ml/c/shitposting";
json.comments = "https://lemmy.ml/post/27104712";
json.description = "submitted by <a href=\"https://lemmy.ml/u/UltraGiGaGigantic/">UltraGiGaGigantic</a> to <a href=\"https://lemmy.ml/c/shitposting/">shitposting</a><br>20 points | <a href=\"https://lemmy.ml/post/27104712/">0 comments</a><br><a href=\"https://lemmy.ml/pictrs/image/5ccfc3c2-f392-4fc0-a5d5-a6f49917e80a.png/">https://lemmy.ml/pictrs/image/5ccfc3c2-f392-4fc0-a5d5-a6f49917e80a.png</a>";
json.enclosure = {};
json.enclosure["@length"] = "0";
json.enclosure["@type"] = "image/png";
json.enclosure["@url"] = "https://lemmy.ml/pictrs/image/5ccfc3c2-f392-4fc0-a5d5-a6f49917e80a.png";
json.guid = "https://lemmy.ml/post/27104712";
json.link = "https://lemmy.ml/post/27104712";
json.pubDate = "Wed, 12 Mar 2025 23:46:24 +0000";
json.title = "It would need more whiskey in it to work.";
json["dc:creator"] = "https://lemmy.ml/u/UltraGiGaGigantic";
json["media:content"] = {};
json["media:content"]["@medium"] = "image";
json["media:content"]["@url"] = "https://lemmy.ml/pictrs/image/5ccfc3c2-f392-4fc0-a5d5-a6f49917e80a.png";
$ curl -s https://slrpnk.net/feeds/local.xml | xq '.rss.channel.item[1]' | gron
json = {};
json.category = {};
json.category["#text"] = "Climate -  truthful information about climate, related activism and politics.";
json.category["@domain"] = "https://slrpnk.net/c/climate";
json.comments = "https://slrpnk.net/post/19442863";
json.description = "submitted by <a href=\"https://lemm.ee/u/neme/">neme</a> to <a href=\"https://slrpnk.net/c/climate/">climate</a><br>4 points | <a href=\"https://slrpnk.net/post/19442863/">1 comments</a><br><a href=\"https://phys.org/news/2025-03-companies-abandoned-climate-consequences.html/">https://phys.org/news/2025-03-companies-abandoned-climate-consequences.html</a>";
json.enclosure = {};
json.enclosure["@length"] = "0";
json.enclosure["@type"] = "text/html;charset=utf-8";
json.enclosure["@url"] = "https://phys.org/news/2025-03-companies-abandoned-climate-consequences.html";
json.guid = "https://slrpnk.net/post/19442863";
json.link = "https://slrpnk.net/post/19442863";
json.pubDate = "Thu, 13 Mar 2025 00:55:05 +0000";
json.title = "Nearly 40% of companies missed or abandoned 2020 climate targets with no consequences, says study";
json["dc:creator"] = "https://lemm.ee/u/neme";
json["media:content"] = {};
json["media:content"]["@medium"] = "image";
json["media:content"]["@url"] = "https://slrpnk.net/api/v3/image_proxy?url=https%3A%2F%2Fscx2.b-cdn.net%2Fgfx%2Fnews%2Fhires%2F2025%2Fbusiness-men.jpg";
$

Edit to add: The W3C feed validator says it’s good, with some warnings 🤷

• https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Flemmy.ml%2Ffeeds%2Flocal.xml
• https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fslrpnk.net%2Ffeeds%2Flocal.xml