Is referring_site in Order resource broken?

[cxxl]

I have been using the referring_site data from the Order JSON resource, see https://shopify.dev/docs/api/admin-rest/2023-10/resources/order#resource-object

Up till some weeks ago, I got many entries of referring_site that were non-null, but since then almost all of them are null.

I tested it myself by clicking on a linkedin post with a link to our shop, then byuing something. The referring_site was null.

What is happening? Has Shopify broken the API? Can somebody confirm this?