Hi Manolo,
The critical path in a project is indicated by a single task or a series of tasks in a project, critical path describes the calculated start date or end date of a project. If a task in a critical path is delayed, then the entire project will be delayed.
We have implemented this support based on the MS Project.
We have analyzed the provided screenshot, the task 11 is laid at the end date of the project, if we change that task the project end date get affected, hence it is marked as critical task.
While on moving the first task it does not affect the project end date hence it is not a critical task.
Please let us know if you need any other assistance.
Thanks,
Suriyaprasanth R.