dynamic_tax_rates is no longer accepted

What changed

Usually ignored rather than rejected, so the call succeeds and does something subtly different.

Affects line_items[].dynamic_tax_rates on POST /v1/checkout/sessions. Grep for it: nothing else will tell you.

Who is affected

Code that sends POST /v1/checkout/sessions (line_items[].dynamic_tax_rates).

Before and after

Code that breaks

await client.post("/v1/checkout/sessions", {
  // dynamic_tax_rates is now ignored, not rejected
  dynamic_tax_rates: value,
});

Based on Stripe’s published API specification. How severity is decided.