Could very well be apophenia. Germany was just one of the countries visited, and we all get spam in a variety of languages all the time, including German.

I don't get spam from a variety of languages.

The only foreign language spam I got was from Pokemon Go after I played it while visiting France & Spain. I received French and Spanish emails from them for years.

I've never received a spam email in German in my entire life. This spam email actually looks to be a legitimate email as after translating it the contents were basically to verify the email address. I don't think I've ever received an email in another language in my entire life and certainly not while I've been at Fastmail (10+ years).