It's challenging to determine causes of defect in potatoes with only several images, and without any history of the problem, how the potatoes are grown, and where.
If the potatoes have always been grown in the same general area of the garden, the likelihood of problems will increase every year.
It's important to use a 4- to 5-year rotation plan in gardens, each year changing where the potatoes are grown. Unfortunately, it's difficult to use a good rotation plan in the often small home gardens, which will help limit populations of damaging insects and/or disease.
Common small defects of potatoes in home gardens, as are shown in your image, may be due to wireworms, the larvae (youngsters) of click beetles.
Does the damage appear to be what has occurred on your potatoes? (To be totally truthful, the damage in the image appears very limited, and easily removed with the peeler.)
The above publication was written for large-scale commercial growers but you might try the simple "traps" the authors describe on page 4. Page 14 has a summary of non-chemical management whereas detailed discussions are as below:
- Page 5: Notice that small areas should have at least 4 traps.
- Page 6 describes what you should do after you trap the insects.
- Page 10 lists resistant potato varieties; some may be available only to commercial growers.
- Page 12 points out that early harvest may decrease, or eliminate, damage.
Only azadirachtin (neem oil) is available for home garden use against wireworms. If used, follow label directions.
If you prefer to have a first-hand diagnosis, you can take several potatoes with typical damage to the Master Gardeners in the Clackamas County Extension Service office. Contact information is at their website: https://extension.oregonstate.edu/clackamas