Arnold Schwarzenegger wasn’t allowed to dub his own role in Terminator to German, as his accent is considered very rural by German/Austrian standards and it would be too ridiculous to have a death machine from the future sound like a hillbilly. – WTF Fun Facts
Source: https://blog.esl-languages.com/blog/learn-languages/celebrities-speak-languages/
WTF Fun Fact – Hillbilly Terminator
Add to this, that German/Austrian Hillbillies have a far worse ring to them here, than the equivalent in the US.