This is expected functionality on upgrades to 8.1. The Gateway Web Interface now uses Federated Identity Providers for authentication, and in order to allow for the same users to be able to login to the Gateway Web Interface as before the upgrade, we automatically create a new internal Ignition IdP and point its user source profile to the system’s user source profile. We then set the new “System Identity Provider” setting to this new internal IdP.
The name “default_0” was used because we attempt to name the new IdP “default”, but there was already an IdP named “default”, so to avoid a collision, we append a unique number at the end.
Starting with RC3, we’re actually going to name it “system_default” instead since the “default” IdP will be a common collision scenario on upgrades from 8.0.x.
As to whether or not you can delete it - I’d make sure you set the “System Identity Provider” to the one you want to use for Gateway Web Interface logins before deleting it. I’m pretty sure the system won’t even allow you to delete the IdP if it is used as the System Identity Provider, since you’d lock yourself out (at which point, you’d have to do a GCU password reset and Gateway restart to commission a new admin account, which will also generate a new internal system IdP).