When using VPN all prices shown in Dollars

-- HikaShop version -- : 6.0.0
-- Joomla version -- : 5.3.1
-- PHP version -- : 8.1.32
-- Browser(s) name and version -- : all
-- Error-message(debug-mod must be tuned on) -- : shows wrong currency

This website is running for years and years but now client comes with remark that someone that orders from the Netherlands is shown the USD prices instead of Euros.

I checked, but when I use VPN (proton in my case) and I use NL still USD is displayed. No mather which country I choose, I delete cookies/caches in between, when using VPN always USD is shown.

Why is that and how can we solve this?

We use Euros, US Dollars and Britisch pounds. And it always worked fine, maybe something in the 6.0 update?