I am a Premium Plus cardholder so it appears I was sent the wrong email template.
Would appear so. The email I received had a picture of the premium plus card (which I have) if yours had the blue card then would seem like an error. It also refers to the premium plus card in the body of the email e.g.
"From today, all Companion Vouchers earned with your British Airways American Express® Premium Plus Card from 1 September 2021 have enhancements to help you Checkout the World, your way."
Key takeaway though is the trigger point for the PP card is still £10,000