Nextcloud server is an open source home cloud implementation. In releases of the 25.0.x branch before 25.0.3 an inefficient fetch operation may impact server performances and/or can lead to a denial of service. This issue has been addressed and it is recommended that the Nextcloud Server is upgraded to 25.0.3. There are no known workarounds for this vulnerability.
https://github.com/nextcloud/server/pull/36016
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-9wmj-gp8v-477j