It’s not easy to see on the Dow samples image but does it look anything like
the top part of this image?
If so, it’s kinda dew. ZWO cameras moreso than QHY cameras suffer from frosting of the front cover slip on the camera. On a dewy night it can be good to slowly cool down the camera or even just wait and it’ll slowly disappear. My ASI094 does have an anti-dew setting but it still takes time to work if I cool down too fast.