The problem is because of something on your system doing an odd redirect. Your system starts with a redirect to a new location and when following that it redirects back to the original. This is where Let's Encrypt fails because it looks like a loop. It isn't because your system processes the second request of the original, but, Let's Encrypt is preventing itself from falling into a loop.
I'm not sure what is doing this redirect or why it is needed. The 11-digit number changes depending on the requestor (maybe its IP?). And, while you will get 200 OK results after this first numeric redirect if you wait a number of minutes (maybe 10?) you will again see the numeric redirect for a fresh request.
You can check this yourself using https://letsdebug.net The first time I ran it I got the redirect failure. But, retrying right away I got All OK result. If you wait long enough you will again see the redirect failure
curl -i -m7 http://api.skie.fun
HTTP/1.0 302 Found
Location: http://api.skie.fun/00913182028/
curl -i -m7 http://api.skie.fun/00913182028/
HTTP/1.0 302 Found
Location: http://api.skie.fun/
curl -i -m7 http://api.skie.fun/
HTTP/1.1 200 OK
Date: Fri, 28 Jul 2023 13:25:21 GMT(
(other headers omitted, data follows)
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