Likely a mismatch of the type of English, if the site treats only EN-US (or EN-UK) as english and hasn't included the other, which would just be a mistake.
Then it might switch to your second preference. Alternatively if your device OS is set to dutch, or have some language system like a virtual keyboard or input manager set to dutch, the site might look at that over the user-agent? Very odd choice if any of those.
Then it might switch to your second preference. Alternatively if your device OS is set to dutch, or have some language system like a virtual keyboard or input manager set to dutch, the site might look at that over the user-agent? Very odd choice if any of those.