I've signed in and I go to the billing page and it just sits there loading. Opening up the web inspector, I see an endless stream of hits to "GET /api/stripe/invoices/next?" that is returning 400 errors (doesn't even have any sort of exponential backoff).

  Ignored request error Error: Unexpected Error (undefined /api/stripe/invoices/next?slug=xyz)
    at _app-9910396bb32daebf.js:1:112690
    at j (main-af5bd4faffaf6d65.js:1:106491)
    at Generator._invoke (main-af5bd4faffaf6d65.js:1:107781)
    at Generator.a.<computed> [as next] (main-af5bd4faffaf6d65.js:1:106894)
    at m (_app-9910396bb32daebf.js:1:110457)
    at g (_app-9910396bb32daebf.js:1:114753)

This is the end of my relationship with Vercel. "Upgraded" automatically isn't the right solution here.