The diagonal stripe across this image is a piece of orbiting debris that passed in front of the spacecraft during the exposure. Another example of space junk is shown in a different set of data as a movie. This movie shows a piece of debris as it moved across the frame between successive readouts of a MULTIACCUM sequence. This piece of junk moved through readouts 9 and 10 of a STEP8 multiaccum.
Reprocess with DQ bits set to eliminate the pixels affected by the junk.