The X/Twitter account “@Markus_Krall” belongs to Dr. Markus Krall, an active social-media commentator1.
Wikipedia describes him as “ein deutscher Unternehmensberater und Autor” (a German business consultant and author), born 10 October 1962 in Aschaffenburg, Germany2.
Business/company records also list him based in Germany (Wörth am Main)34.
So the account holder known as markus_krall is indeed German.