api.GPUAdapter.isFallbackAdapter - Not supported in Firefox

[evilpie]

What type of issue is this?

Incorrect support data (example: BrowserX says "86" but support was added in "40")

What information was incorrect, unhelpful, or incomplete?

GPUAdapter.isFallbackAdapter was deprecated and removed. As far as I know it never shipped in Firefox.

What browsers does this problem apply to, if applicable?

Firefox

What did you expect to see?

Not supported

Did you test this? If so, how?

Yes.

  const adapter = await navigator.gpu.requestAdapter();
  console.log(adapter);

Can you link to any release notes, bugs, pull requests, or MDN pages related to this?

No response

Do you have anything more you want to share?

No response

MDN URL

https://developer.mozilla.org/en-US/docs/Web/API/GPUAdapter/isFallbackAdapter

MDN metadata

MDN page report details

• Query: api.GPUAdapter.isFallbackAdapter
• Report started: 2026-02-12T17:36:15.806Z

[caugner]

https://bugzilla.mozilla.org/show_bug.cgi?id=1955057 suggests it was supported before Firefox 141, when isFallbackAdapter was moved to GPUAdapterInfo.

Edit: So it was only available in Nightly, and was (re)moved before it shipped.