It looks like your issue is related to DNS propagation or incorrect TXT record placement. Here’s how to fix it:
Check DNS Propagation – Use dnschecker.org or Google Dig to see if the TXT record is visible globally.
Verify TXT Record Entry – Ensure _acme-challenge.sven-kilcher.dev is correctly added under the TXT type in your DNS manager. Double-check for typos.
Wait for Propagation – Some DNS providers take time to update, sometimes up to 24 hours.
Check Your DNS Provider – If using Cloudflare or another service, ensure the record is added in the right place.
Retry After Rate Limit – Since you've hit the limit, wait an hour, delete failed attempts, and restart verification.
Best Alternative: If Let’s Encrypt fails repeatedly, consider a getting cheap Wildcard SSL cert. You can easily get one from CheapSSLShop as they are one of the cheapest SSL resellers.
Hope this helps!