Issue authenticating with *service-to-service not engaged* error message

Afternoon, I have been successfully connecting to Hubspot from an AWS Lambda for years using the Hubspot npm package - https://www.npmjs.com/package/hubspot.
I noticed today it was not syncing and looked at the logs to see the error below.
Do I need to do more config in Hubspot now, or is there additional information I need to send at Auth time?
Thanks,
Doug

====================================================

<html>\n’ +
’ <head>\n’ +
’ <title>Error - content not found due to bad url (404)</title>\n’ +
’ </head>\n’ +
’ <body>\n’ +
’ <h1>Error - content not found due to bad url (404)</h1>\n’ +
` <h2>401 - {“status”:“error”,“message”:“Any of the listed authentication credentials are missing”,“correlationId”:“blah”,“engagement”:{“service-to-service”:“service-to-service not engaged. Metadata for service-to-service request not found.”,“internal-cookie”:“internal-cookie not engaged. You can get a new internal auth cookie for host ‘api.hubapi.com’ by visiting following link from your current browser window: Sign in ・ Cloudflare Access .”,“app-cookie”:“app-cookie not engaged. App cookie is not present on the request.”}}</h2>\n` +
` <h3>StatusCodeError: 401 - {“status”:“error”,“message”:“Any of the listed authentication credentials are missing”,“correlationId”:“blah”,“engagement”:{“service-to-service”:“service-to-service not engaged. Metadata for service-to-service request not found.”,“internal-cookie”:“internal-cookie not engaged. You can get a new internal auth cookie for host ‘api.hubapi.com’ by visiting following link from your current browser window: Sign in ・ Cloudflare Access .”,“app-cookie”:“app-cookie not engaged. App cookie is not present on the request.”}}\n</h3> \n’ +
’ </body>\n’ +
’ </html>

Hi @Dougality and welcome, we are delighted to see you here! :hugs:
Thanks for reaching out to the HubSpot Community!
For information, I’d like to share this documentation “OAuth” that might be of interest.
And you might want to take a look at the solution from @coldrickjack on this similar post “Any of the listed authentication credentials are missing” that might help you!
Also, I’d love to ask our Top Experts: Hi @coldrickjack, @lindahl and @skimura do you have suggestions to help @Dougality, please?
Have a lovely day and thanks so much in advance for your help! :heart:
Bérangère