I created a dimension in NX (the red marked area).
Why does it look like that, it has something different than regular ones....
And it happens only in NX (no similar issue in Catia and SW).
Is it like that because of length? (Sorry, I do not have experience with GD&T)....
Looks like a foreshortened dimension due to the view being broken. The wire is much longer than what is shown in view, so the wire is broken. And then the dimension should be shown as such when the dimension spans the broken out area. Not sure if broken is the correct term...
As @rickyt mentioned, that symbol is called the 'Foreshortening Symbol' which will be created after using the 'View Break'.
I am not sure at the moment if you can remove the symbol on the existing dimension, but there is a Drafting Preference that can be helpful if you do not wish to have it.