I suppose it's this, https://www.howtogeek.com/407924/how-to-turn-translation-on-...
he has a German Google Chrome, your page said it was English, he has set it to automatically translate from English to German at some point in the past and forgot about it, or his company does it and never told him.
I tried to replicate this scenario on Browserstack but that didn't work. The content of the page is in German. The Chrome built in translation showed the language as unknown. Also most of the text seemed right he only pointed out these two words.