On the old bugtracker site, activity such as comments could be sorted by new and this was the default setting. This functionality is absent from the new bugtracker site.
Old site example: https://bugs-legacy.mojang.com/browse/MC-2836
New site example: https://report.bugs.mojang.com/servicedesk/customer/portal/2/MC-2836
This is not something we can solve, however feel free to vote for it here: https://jira.atlassian.com/browse/JSDCLOUD-8484