ServiceEndpointProxy activity on ADO Service Connection

I have an ADO Service Connection which I don't think is being used by any pipelines but I still see regular entries in the usage history like:

Type: ServiceEndpointProxy

Details: ServicePrincipalSignInAudience

I've not been able to find any information about what causes this. What is causing this activity and will deleting the service connection adversely affect anything assuming this is the only thing using it?