Affected Versions:
If Region is US:
Nightly 82 - affected since CC is enabled by default
Beta 81 - affected since CC is enabled by default
Release 80 - affected but behind disabled pref

Tested on:
Windows 10 x64
MacOS 10.13

Steps to reproduce:

1. Reach Ebay.com payment form (the site autofills the Cardholder Name field)
2. Click on the Card Number or Expiration date fields and choose to fill in with a saved CC card

Expected Results:
All the expected fields should be autofilled with the saved CC values - including the First and Last name fields
The fields should be highlighted with the yellow color specific to form autofill.

Actual Results:

1. Since the Name fields were filled by the site on page load, CC autofill works only for the Number and Expiry Date.
2. The auto-filled fields are not highlighted.
   Recording: https://streamable.com/7eqrme

Notes:
Not reproducible on Chrome, check the attached recording for comparison.
Clearing out the Name fields that were filled in by the site will make the autofill to work correctly for those fields too.

Regression-Range:
Doesn't seem to be a regression, in Nightly 78 CC autofill doesn't work at all for this site and starting with Nightly 79 it works as it is now. This is not Bug 1655407, since that is happening on walmart.ca

Severity Suggestion:
Even if Chrome handles this better, this is not a severe and permanent malfunction given it has an easy way to make it work correctly by clearing out all the filled-in fields by the site and toggle CC autofill afterwards, thus suggesting S3-S4 severity.

The severity field is not set for this bug.
:jimm, could you have a look please?

For more information, please visit auto_nag documentation.

This issue is also reproducible in latest Nightly 85.0a1 (build id: 20201117215529) on ebay.ca. Updating the flags and summary accordingly.

I just tested on ebay.com, the cc #, date, and card holder name were filled successfully.

I can still reproduce this on the latest Nightly 86. As mentioned in the bug report, reaching the payment form will require going through the shipping address before. Due to this, the site will use the captured Name from the shipping form and fill it in on the payment form.
If I delete the pre-filled name data, the credentials will be fully filled in afterwards, as expected. Otherwise, the pre-filled name fields will not be modified upon seleting any saved CC entry from the dropdowns.