Bug? Default transcript of english video comes back as spanish

I want to fetch the default transcript for a video (not knowing ahead of time what language is spoken in the video). For this video of a woman speaking english teaching German I get a transcript in Spanish when I don't specify a language (or use auto in the playground). When I test with the playground feature of another API provider it returns an English transcript.

https://www.youtube.com/watch?v=MOtqMNKs0Jw