Steps to reproduce:
- git clone https://github.com/J-Siu/browser_identity_test.git
- Load extension from disk
- Open a new tab
- Open console
It set an empty new tab page and print in console log with following code:
console.log(browser.identity)
console.log(browser.identity.getRedirectURL())
console.log(chrome.identity)
console.log(chrome.identity.getRedirectURL())
Following is result:

Expected behavior:
According to https://browser.kagi.com/WebExtensions-API-Support.html row:285, identity api is supported.
Tested from Firefox:

Orion, OS version; hardware type:
- MacOS 12.5.1
- Macbook Air
- Version 0.99.119-beta (WebKit 615.1.1)
Image/Video:
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