Tested with latest Nightly 96.0a1 (2021-11-03) using Windows 10 and macOS 10.15 and I can confirm that this issue is fixed by bug 1687681. The CC save doorhanger is displayed accordingly and the date format is correct.
Bug 1688615 Comment 2 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Tested with latest Nightly 96.0a1 (2021-11-03) using Windows 10 and macOS 10.15 and I can confirm that this issue is fixed by bug 1687681. The date format is correct.