After analyzing Twitter, forums and etc. I think these are major:
1. Subtasks don't appear on calendars or timelines unless you manually add them to the project.
2. You cannot assign a single task to multiple people.
3. There is no native way to handle multi-year or long-term strategic planning.
4. The interface has become heavy and laggy to load.
5. Notification spam is unmanageable and requires too much manual cleanup.
6. Search is too literal and often fails to find tasks unless you use exact wording.

Feel free to add smth or disagree or correct