buganizer.corp.google.com is an alias for uberproxy.l.google.com.
uberproxy.l.google.com has address 142.250.141.129
uberproxy.l.google.com has IPv6 address 2607:f8b0:4023:c0b::81
Google's corp services are publicly accessible in that sense - but you're not getting through the proxy without valid credentials and (in most cases) device identity verification.