Hi,
My understanding is that the legacy commenting experience has now been deprecated and is no longer acccessible.
There will have been notifications advising of this sent to your system admins as a system notification in Workfront. The release notes here on Experience League also advise of the upcoming changes.
I recommend submitting an idea on the forum outlining the missing functionality you would like to see return. Adobe do review these feature requests and imay accommodate in future product releases.
Best Regards,
Rich.