Bungled programming, I'll bet. The programmers behind Amazon emails cannot even get simple HTML right. They regularly send me mails showing & etc.
The LLM was looping. :-)
Turns out it is some marketing bullshit to force what some mail clients show in the preview. They use a large pad of joiners / combiners / soft punctuation / etc. to prevent the mail client from choosing text after the pad for the content preview.