Comment 15 for bug 1927742

You can see the problem even without actual dolphin, curl is enough. In focal with apache set up as above:

$> cd /var/www/webdav
$> mkdir a
$> chown www-data: a
$> curl -I -X DELETE http://localhost/a
HTTP/1.1 301 Moved Permanently
Date: Wed, 09 Aug 2023 16:05:00 GMT
Server: Apache/2.4.41 (Ubuntu)
Location: http://localhost/a/
Content-Length: 302
Content-Type: text/html; charset=iso-8859-1
$> curl -I -X DELETE -A 'prefix Konqueror/5' http://localhost/a
HTTP/1.1 301 Moved Permanently
Date: Wed, 09 Aug 2023 16:06:04 GMT
Server: Apache/2.4.41 (Ubuntu)
Location: http://localhost/a/
Content-Length: 302
Content-Type: text/html; charset=iso-8859-1
$> curl -I -X DELETE -A 'prefix Konqueror/4' http://localhost/a
HTTP/1.1 204 No Content
Date: Wed, 09 Aug 2023 16:09:28 GMT
Server: Apache/2.4.41 (Ubuntu)

See? It rejects (with redirect) curl's own user agent as well as Konqueror/5, which is dolphin in focal. But Konqueror/4 is OK since it is mentioned in `BrowserMatch " Konqueror/4" redirect-carefully` in /etc/apache2/mods-available/setenvif.conf