Why does LineGeometry form a loop with the start and end points?

The line I create has an array of vectors which when drawn joins the last end points.

There is no LineGeometry, but
2021-02-12 08.37.49

See also Drawing lines: three.js docs

Hey, apologies for LineGeometry.
Used line but didn’t work.

Array of vectors seem to create a loop.

Can you make a live example? e.g. jsfiddle or codepen

Look there discourse.threejs.hofk.de

2021-02-12 09.10.47

in the Collection of examples from discourse.threejs.org

See also LineRelatedSquare

Could you be more particular in description of the problem?
How you create points? Do you use splines? What geometry do you use?
Looking at the picture, I would say, that there is no using of lines, but something like TubeGeometry with .closed property set to true.

As @hofk mentioned, you’d better provide an editable live code example, that demonstrates the issue, thus you’ll get help/solution quicker.