As long as there are not errors in the Discourse RSS feed, the responsibility for how the feed is displayed is with the feed reader, not with Discourse. Checking the feed here shows that the feed is valid, with a few minor issues noted: Feed Validator Results: https://meta.discourse.org/latest.rss.
I don’t think the issue that are noted are causing the display problems you are seeing on Telegram. Have you tried Telegram with other RSS feeds?