As you may have noticed, the VPN badge now appears in the iOS status bar if 1Blocker's Firewall is running, and here's why this is the expected behavior.
Some improvements made in the 1Blocker 5.1 update require the VPN icon now, so iOS places it to the status bar whenever Firewall is running in the DNS Proxy mode.
We would change it, but the system always does it automatically.
The update made Firewall more consistent and reliable.
The tool itself works the same way as before under the hood, so all blocking is still done locally. Also, Firewall is compatible with almost all apps now, and it even supports some Personal VPN configurations.
More info here: Firewall and other VPNs