System Information
Operating system: Windows 10
Graphics card: Nvidia RTX 3070

Blender Version
3.1 Alpha

Short description of error
The curve factor and lenght for the last segment (the one who closes the cyclic curve) gets a factor or 1 to 0 or a lenght or max lenght to 0.

Exact steps for others to reproduce the error
I think this can't be expected behavior because the information ir incorrect, if you make calculations with the lenght or factor you will get wrong results.

The factor goes form 0 to 1 on the last point and then to close the curve it goes fom 1 to 0.
The lenght show value from 0 meter to 3 meters for exameple and then the last segment has 3 meters to 0, we can agree that this last segment is not 3 meters long. And the total lenght is different from the circunference because it's not adding the last segment to the lenght.

Maybe this is not possible because the info is on the control points? but in any case the result is wrong, we can't use it correctly.