Please let us know if you do see it again. Per bug 1971874 comment 5, it looks like (as of today at least) the site's JavaScript has been fixed to no longer trigger this problem.
Bug 1972808 Comment 8 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Please let us know if you do see it again. Per bug 1971874 comment 5 (specifically the `Math.max(0,...)` quoted there to avoid negative values), it looks like (as of today at least) the site's JavaScript has been fixed to no longer trigger this problem, or at least the problem that was identified in the discourse thread linked here.