A cloud-based identity and access management service for securing user authentication and resource access
To answer the main question on how to find/stop this - look in the Enterprise Applications list for your Azure AD/Entra ID tenant and see if any of the applications there stand out as being named similarly to the URL that the error contains. I don't believe there is a way to list out all configured provisioning jobs in a tenant - any attempt to do that would require making a List Jobs call to MS Graph API for every service principal, or at least the ones that are Enterprise Apps - I'm not sure how that can be determined via MS Graph, however.
For reference: https://learn.microsoft.com/en-us/graph/api/synchronization-synchronization-list-jobs?view=graph-rest-beta&tabs=http
If you have too many AAD/Entra tenants for this to be feasible, if you open a support case via the Entra portal our support engineers may be able to help you locate the source of the error as well.
Separately, to quickly cover the meaning of the actual error - Entra ID Provisioning is attempting to start a provisioning/sync cycle with the SCIM server at the base URL in the error message, but the server is returning a 500 series HTTP response - in this case, it looks like 500/Internal Server Error. The actual issue is with the SCIM server/app, not Entra.