The website of the ministry of foreign affairs of Cambodia https://www.mfaic.gov.kh/ returns a 403 only for Qt WebEngine 6.8+

Most browsers are working fine:

• Brave 1.82.170
• Chrome 140
• curl 8.5.0
• Edge 140
• Falkon 24.01.75 (Qt WebEngine 5.15.16)
• Firefox 143.0.1
• simplebrowser demo with Qt 6.7.3

But when using the simplebrowser demo with Qt 6.8+ , I directly get a 403 error.
I have tried to modify QtWebEngine headers to make them look like another browser without any luck.
However if I take the simplebrowser demo with a Qt version that receives a 403, and from the dev tools I copy the network request "as cURL", the request works fine when run in a terminal.

IMHO it seems to indicate that QtWebEngine does something "wrong" during the handshake.

Note that I know it is a very niche issue, but if all other browsers can access this site, why not Qt WebEngine? Also my biggest concern is that it could impact other websites.