As another voice to this thread, I thoroughly agree with the complaints mentioned above. The new "modern" comments system is a major downgrade and needs to have a "Use Classic Comments" setting in the Options menu. As a professional editor, losing the ability to see comments in line with the tracked changes, losing the ability to use complex formatting in the comments, and losing comment compatibility with my clients who use older versions of Microsoft Word are just a few of the setbacks this change has caused my business.
The forcible adoption of features that remove important (for us) functionality in exchange for useless functionality (for us) is not what we signed up for with Microsoft 365 subscriptions. Microsoft Word should be providing more tools, not removing functionality from existing ones.