Hello, and Welcome to the HP Support Community!
When you do a copy, do you use the Document feeder, or place the original manually on the flat glass?
If the streaks ONLY show when you use the Document feeder, look at the thin strip of glass at the end of the flat glass bed (under the doc feeder). Look closely for some specs of paper, dirt, etc. right where the streak is located on the copy.
(See #3 below).

Use a soft brush or towel to gentle clean the window. Good luck!
WyreNut
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