Two address families
IPv4 uses shorter addresses and widespread address sharing. IPv6 provides a much larger address space and often direct addressing for interfaces.
Neither protocol is automatically private or unsafe.
IPv6 is not inherently a leak
The relevant question is whether traffic bypasses the route or policy you intended, not whether IPv6 exists.
A working IPv6 connection should not be penalized merely for being available.
Temporary addresses help
Many systems use privacy extensions that rotate interface identifiers and reduce long-term address stability.
Provider prefixes and other signals can still provide network context.
Dual-stack choices vary
Browsers and operating systems choose between available paths based on reachability and performance.
A normal dual-stack hostname does not guarantee which family a request will use.
Forced probes provide clearer evidence
Separate IPv4-only and IPv6-only hosts can show whether each family reaches the internet through the expected route.
Those probes require independent infrastructure and remain inconclusive until the service is deployed and verified.