It's super frustrating, but that's the distance the machine needs to "grab" first to pull the tape out, think of it as white margins when you print A4 pictures
I have already asked this question. It's probably a problem with the design. I deal with it in two ways: (1) In the print dialogue, switch off the cut in the options, print endlessly and cut by hand. (2) I buy the much cheaper "generic adhesive rolls" from Amazon, ignore the 2cm scrap and need it as a label that I write on by hand with a waterproof pen.