adding mimikama RSS gives error while other rss readers work

[TabForce]

adding https://www.mimikama.org/feed results in internal server error:

Fehler	index	FeedIo\Adapter\ServerErrorException: Client error: GET https://www.mimikama.org/feed resulted in a 403 Forbidden response: <title>Just a moment...</title> <meta http-equiv="Content-Type" conte (truncated...)

No valid feed found at URL, attempting auto discovery

Warnung	news	https://www.mimikama.org/feed read error : Client error: GET https://www.mimikama.org/feed resulted in a 403 Forbidden response: <title>Just a moment...</title> <meta http-equiv="Content-Type" conte (truncated...)

Happens with and without auto detection

News app 21.0

[Grotax]

They are blocking the request, maybe due to the timestamp that is send which is in the past.

Or some other reason