URL: https://business.apple.com/
Browser / Version: Firefox 64.0
Operating System: Mac OS X 10.13
Tested Another Browser: Yes
Problem type: Site is not usable
Description: Can't use Firefox, recommends other browsers
Steps to Reproduce:
Browser Configuration
_From webcompat.com with 鉂わ笍_
Contacted Apple about the issue.
Issue still exists. Following up with Apple.
The issue is still reproducible on my side.

Tested with:
Browser / Version: Firefox Nightly 69.0a1 (2019-06-10)
Operating System: Windows 10 Pro
Any update on this?
Unfortunately, no changes yet.
Perhaps a user agent override should be added? They really don't seem to care about Firefox at all which is a huge shame.
But you have compatible Apple ID to tests, maybe Apple added many other shames to exclude Firefox?
But you have compatible Apple ID to tests, maybe Apple added many other shames to exclude Firefox?
Wouldn't it still be better to have it work for the most part than not work at all?
But I mean, is there any trap in the application that a change of UA after login does not work longer?
My Apple ID is not assigned to a rare company, so I can't check if e.g. the page after login doesn't crash/broken - because it's based on Blink/Webkit compatible CSS and there's no firefox for emergency support of not recommended Chromium Blink/Apple WebKit syntax.
Most helpful comment
Perhaps a user agent override should be added? They really don't seem to care about Firefox at all which is a huge shame.