[Закрытые] Ordering an item on the German page redirects me on the English page

Background of the issue:
I'm in the German version of the website скрытая ссылка and this issue only occurs when I'm logged in. When I add a product to the cart, the Cart that appears is in English. The translation is not the biggest problem, but the link in the buttons also directs to the English version.

Symptoms:
Ordering an item on the German page redirects me to the English page, and the cart appears in English with links directing to the English version.

Questions:
Why does adding a product to the cart on the German page redirect me to the English page?
Why does the cart appear in English when I'm on the German version of the website?
Why do the links in the cart buttons direct to the English version?