It's not necessarily a concern.
The lapse rate is the portion of authorities that Parliament provides to the departments. They have the capacity to spend up to these amounts. The lapse rate is the portion that ends up not being spent. It can be a concern if it means departments are unable to spend in areas of priorities. It could be a concern if there are dire needs that are not met because departments cannot implement some initiatives quickly enough. However, it can also be a good thing if it avoids wasteful spending—spending for the sake of using all the appropriation.
It has to be looked at with a specific lens. You cannot just say that a lapse is a bad thing in absolute terms or a good thing. One has to look at the reasons behind a certain amount of lapse.