Thank you very much! That was probably also the reason why my site was suddenly no longer accessible. I must have played with the Cloudflare settings a bit too much.
Since my old domain provider only supported DNSSec inadequately & incorrectly, I had to look for something new. That’s when Cloudflare came to mind. The free plan is completely sufficient for me. It’s a shame that the tariffs don’t even scale reasonably to the requirements.