Thanks for your question.

There are various diseases and conditions that produce leaf spotting and leaf changes in potatoes.  These include:

1).   Early Blight:  This is a fungal (Alternaria solani) disease that causes dark spots with concentric rings on leaves.  Leaf curling also occurs.

2). Late Blight:  Another fungal (Phytophthora infestans) disease producing brown and necrotic regions in the leaf.

3).  Potato Virus Y (PVY) causes mottled, curled, and stunted leaves. This is generally seen in plants infected by aphids.

4).  Infection by potato leafroll virus (PLRV) leads to upward leaf rolling and yellowing of the leaf margins.

5).  Lack of water and/or significant heat can cause leaf curling as the plant attempts to reduce water loss.

6).  Lack of essential nutrients like potassium or magnesium can cause leaf spotting and curling.

My point is:  iit is very difficult to make an accurate and specific diagnosis of a plant disease just from pictures.  Unfortunately, without knowing the precise cause of a condition, no real purpose is served by applying various fungicides or utilizing other chemical treatments.

See the following for some additional information:

https://vegpath.plantpath.wisc.edu/diseases/potato-brown-spot-and-black-pit/ - :~:text=Brown spot and Black pit are fungal diseases of potato,of leaf or petiole surface.

https://www.canr.msu.edu/resources/brown_leaf_spot_e3182

https://www.canr.msu.edu/news/brown_leaf_spot_in_potatoes_plan_for_this_early_blight_look_alike_in_2013

https://apps.extension.umn.edu/garden/diagnose/plant/vegetable/potato/leavesspots.html

If you are serious about getting to the bottom of things, consider submitting plant samples to a diagnostic disease laboratory for an analysis. This would be a definitive way to arrive at a decisive answer to your question.  With that information, you would know exactly what remedial steps should be taken.  Both Wisconsin and Minnesota have excellent labs to do this. Before submitting anything to either of them, call first as to what type of samples should be submitted. Both have a nominal charge for their analysis. See:

https://pdc.umn.edu/

https://pddc.wisc.edu/clinic-overview/

Good luck. Please keep us apprised of your situation as we will be glad to answer any further questions that might arise.