Before you read the result
What Brave VPN documents about these signals
The points below come from Brave's own product pages and announcements for its Firewall plus VPN offering.
Built into a browser, applied to the device
Brave documents the feature as protecting internet traffic on every application on your device, even outside Brave, and describes it as network-level protection rather than a proxy inside the browser. Unlike a browser VPN, a check run in a different browser on the same machine should therefore also show the tunnel address, and one that does not is worth investigating rather than expecting.
The killswitch is listed for iOS only
Brave's own feature list names a killswitch and marks it iOS only. On Windows, macOS and Android there is consequently no documented feature to blame when a check catches your own address after a reconnect. The question becomes what was reachable during the gap, which no single reading can answer, and which is why a recorded disconnect is more informative here than elsewhere.
Guardian runs it, and DNSFilter owns Guardian
Brave states that the service is powered by Guardian, and describes Guardian as a firewall and VPN technology platform that was acquired by DNSFilter. An address lookup naming an operator you did not expect is consistent with that arrangement, so compare the network behind your exit address against the region you selected rather than against the word Brave.
A firewall and a VPN are two separate halves
Brave frames the product as a firewall plus a VPN and is explicit about why: a VPN encrypts your internet traffic but cannot block harmful trackers and other online nuisances, which is the firewall half's job. A resource that will not load partway through a check may have been blocked by the firewall rather than having failed on the network.
Smart proxying, platforms and device count
Brave lists smart proxying, for reaching sites and applications that try to block VPN traffic, as available on iOS and desktop, and lists Android, iOS, macOS and Windows with Linux described as coming. One subscription is documented as covering up to ten devices. That last number is worth remembering when two of your devices give different answers to the same check.