I got a response from both TFL and Greater Anglia and they are basically saying it is the other’s issue
TFL
Thank you for your follow up email of 11 March about the price of fares from Stansted Mountfitchet to Tottenham Hale.
As this is not a TfL service, it is my understanding that Greater Anglia would set the fares for this leg of your journey, so I can suggest you contact them here.
Greater Anglia
hank you for contacting Greater Anglia Customer Relations regarding contactless fares for your journey from Stansted Mountfitchet to Walthamstow Central.
Please accept my apologies for any confusion regarding the pricing and peak/off-peak structure when using contactless for this journey.
The fare structure for contactless pay-as-you-go travel within the London area is set and managed by Transport for London. As a result, Greater Anglia does not control how these fares are calculated or applied.
For detailed guidance on how the fare would be charged for your specific journey, including how peak and off-peak rates apply when travelling via stations such as Tottenham Hale and Walthamstow Central, I would recommend contacting Transport for London directly. They will be best placed to explain how the contactless fare system would calculate the cost of your journey.