I've just gone down a rabbit hole around when a phytosanitary certificate is / is not required. The Gov.uk website says "You do not need phytosanitary certificates for plant products such as fruit and vegetables that have been processed and packaged", I also found other websites mentioning that if processed plant products are "commercially sealed" then certificates are not required.

I've also checked that maple syrup (or to be precise, the processed sap of acer saccharum) is not on any restricted product list.

I never imagined this would be such a can of worms! Thanks again