SP.Social APIs stopped working recently #11009

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

SharePoint REST API

Developer environment

Windows

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

This is not a development specific issue. So it affects all versions and all tenants.

Describe the bug / error

The SP.Social API for following and unfollowing content has stopped working and returns an code '3'. These endpoints have been working without issue for years. Recently, they started returning '3' which is an error.

SP.Social API
https://learn.microsoft.com/en-us/sharepoint/dev/general-development/following-people-and-content-rest-api-reference-for-sharepoint

We first had this issue logged in our PnPjs repo pnp/pnpjs#3364 . Upon further testing, it is happening across all tenants and not related to PnPjs.

Steps to reproduce

We used PnPjs to reproduce https://pnp.github.io/pnpjs/sp/social/

For testing we executing a following / unfollow calls for both sites and documents

import { spfi } from "@pnp/sp";
import { SocialActorType } from "@pnp/sp/social";

const sp = spfi(...);
const r1 = await sp.social.follow({
    ActorType: SocialActorType.Site,
    ContentUri: "htts://tenant.sharepoint.com/sites/site",
});

Follow returns 200 but return { ..., "value": 3 } which means according to the docs that an internal error happend

Expected behavior

When using the SP.Social APIs, the following and unfollowing content endpoints should follow and unfollow content and successfully return a 200 with { ..., "value": 2 }