Q.possible blight on potatoes
I wonder if you could help me with a problem. I have recently noticed some of my potato plants have started to show brown patches on the leaves, and some of the haulms have dropped. I am not sure that it is blight, as there has been no sign of any white spores on the underside of the leaves. The potatoes are available to harvest now and I have dug up several plants and the tubers look ok but I am still concerned. Could there be another reason for this or would I be wise to cut all haulms down and leave the tubers in the ground for a few weeks?

Here is a link to help identify a potato blight.
https://www.gardeningknowhow.com/edible/vegetables/potato/potato-blight-diseases.htm