Header Script showing up on Mobile?

Site URL: https://www.cotswoldforager.co.uk/products/gift-vouchers

Only just noticed - maybe due to an update on Squarespace - that my mobile pages are now showing the script in the header at the top of the page.

It hasn't been a problem up until the last day or so, although it does show briefly when loading on both mobile and desktop, but I have no idea how to fix this...

Any help would be hugely appreciated