Using Cloudflare on your website could be blocking RSS users

In any case, it blocks German Telekom users. There is an ongoing dispute between Cloudflare and Telekom as to who pays for the traffic costs. Telekom is therefore throttling connections to Cloudflare. This is the reason why we can no longer use Cloudflare.

as much as I am not a fan of cloudflare's practices, in this particular case DTAG seems to be the party at fault.

There is no dispute. Telekom is not peering on public exchanges and wants ransom as in expensive private ip-transit contracts from everyone. Their customers are used as a bargain for this. Recently Meta stopped playing that game and Cloudflare never did afaik. Telekom could solve a part of this problem with a few 100k€ and a few weeks time if they would peer at the bigger German exchanges. If every big ISP would act like them the Internet would be dead.