I don't know what the IPv6 bug is but thought it could be related with IPv6 being dislabled in the domain.
So decided to create a subdomain with IPv6 enabled to check if it still gets detected. It does, https://ipv6.bigpress.net gets detected
The detection happens both with the extension installed (Browser Guard) and the Windows desktop application.
Malwarebytes
www.malwarebytes.com
-Log Details-
Protection Event Date: 2/16/24
Protection Event Time: 6:07 AM
Log File: 54bae5e2-cc89-11ee-8bcb-bc2411dc42e8.json
-Software Information-
Version: 4.6.8.311
Components Version: 1.0.2259
Update Package Version: 1.0.80993
License: Trial
-System Information-
OS: Windows 10 (Build 19045.3086)
CPU: x64
File System: NTFS
User: System
-Blocked Website Details-
Malicious Website: 1
, C:\Program Files\Google\Chrome\Application\chrome.exe, Blocked, -1, -1, 0.0.0, ,
-Website Data-
Category: Phishing
Domain: ipv6.bigpress.net
IP Address: 165.22.22.250
Port: 80
Type: Outbound
File: C:\Program Files\Google\Chrome\Application\chrome.exe
(end)