Is this about RSS as is or certain RSS readers can help with this cloudflare script checker?
... that was I was going to ask, and I have just found a solution, for those who use Firefox
https://addons.mozilla.org/en-US/firefox/addon/feedbroreader/?src=search works fine with cloudflare blocking
IMPORTANT: how to make this thing working
Add/import your feeds into addon.
Put default scan interval in the settings to 30 minutes and update threads to 2.
Open any mangadex page right after you start, yes, as soon as you start Firefox - to bypass any captchas and limits put on you by Cloudflare.
Assuming you have Firefox opened for reasonable time(1 hour+) - all feeds will update in due time.
May you can put scan interval less than 30 min, like 15 or 10, I did not test.