I have reproduced this issue using Firefox 71.0a1 (2019.08.11) on Win 10 x64. I can confirm this issue is fixed, I verified using Firefox 70.0b14 on Win 10 x64, macOS 10.13 and Ubuntu 18.04 x64.
Bug 1573063 Comment 11 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
I have reproduced this issue using Firefox 70.0a1 (2019.08.11) on Win 10 x64. I can confirm this issue is fixed, I verified using Firefox 70.0b14 on Win 10 x64, macOS 10.13 and Ubuntu 18.04 x64.