Yes it’s not blight, possibly old age, you need to say if they are first earlies, second earlies or maincrop.
If first early I would lift them and plant your new veg immediately.
If ever it were blight, you can still plant anything else after.
Plus the advice about leaving tubers in the soil only applies to potatoes for storage.
The theory for that is so that blight spores which may be briefly alive in the soil do not infect tubers while lifting.
In practice I find it makes no difference and I lift to store immediately, just make sure potato skins are dry before placing in sacks.