Anyone else getting double 401s on every Power Query Web.Contents request since today? (March 1st)

I have an API that Power Query connects to using Organizational Account authentication (Entra ID / Azure AD). The API returns the standard WWW-Authenticate challenge header so Power Query can discover the auth endpoint and acquire a token.

The expected behavior was: Power Query sends one unauthenticated request, gets the 401 challenge, acquires a token, and then reuses it for all subsequent requests — so you'd see one initial 401 followed by all 200s.

Starting today (March 1st), every single request from Power Query now does this:

• 1st request: no Authorization header → 401 (~35µs)
• 2nd request: still no Authorization header → 401 (~35µs)
• 3rd request: valid token → 200

This happens on every call, not just the first one. It's like Power Query stopped caching the token between Web.Contents calls and is repeating the full discovery flow each time.

Nothing changed on my backend — same middleware, same Azure App Registration, same config. The timing (first of the month) makes me think an Office/Excel update rolled out overnight that changed something in how Power Query handles the OAuth challenge flow.

Is anyone else seeing this?