I occasionally encounter feeds that my feed reader cannot subscribe to because the site uses Cloudflare DDoS protection, which Cloudflare implements in a manner contrary to the ethics of the open web, in the process making it near impossible for feed readers or read-it-later services to access the content.

I have no simple work-around for such RSS feeds - they are effectively rendered useless by Cloudflare's discriminatory and user-hostile blocking implementation.

Cloudflare themselves claim doing nothing wrong, and that it is in fact the site operators that have misconfigured their Cloudflare firewall and that users should contact the site operator. Which is simply ridiculous.
If Cloudflare cared at all about the open web, this issue would not be relegated to a few obscure forum posts. They could also easily implement some form of automatic exemption from their page blocking for common feed endpoints, such as /feed, rss.xml and similar.

• Cloudflare considered harmful, 2019-10-23, Hugo Landau
• https://git.nixnet.services/you/stop_cloudflare
• Stay away from Cloudflare, 2017-12-20, unixsheikh.com
• https://news.ycombinator.com/item?id=12646055 (thread on the subject of Cloudflare and RSS)
• https://reddit.com/r/selfhosted/comments/qars38/rss_feed_behind_cloudflare_protection/
• https://stackoverflow.com/questions/11886711/curl-cant-fetch-rss-from-website-because-of-cloudflare
• https://github.com/VeNoMouS/cloudscraper (a work-around in Python, but I don't know how to incorporate with TinyTinyRSS...)

My list of places where you can find RSS feeds. Quality may vary, buyer beware.

• RSS Database by FeedSpot. I have no knowledge of the quality of these collections.
• https://codeberg.org/solarchemist/svenska-tidskrifter-rss - my own collection of RSS feeds to Swedish newspapers.

Note that this is a German affair.
Still, the hall of fame (below) might give you some ideas.

• https://www.nfdi4chem.de/fair-data-hall-of-fame