Well, you were right! Thx for insisting. I wasn't able to review full rights of the application (or at least they were misleading) but eventually I reinstalled it and it worked.Side note: it seems to me that the example here: https://shopify.dev/tut...

 

It's the main root account.

I got this error using the Shopify GraphiQL App from my shop page.(At the end I don't mean to use it through an app but directly in a lambda function) 

I get a "ProductUpdate access denied" when trying your method.Is it possible to update public product metafield?