Strawberries (including pineberries) are hybrids between Frageria chiloensis var gigantea and F. virginiana. F. chiloensis grows along the beach from about British Columbia down to at least California, makes it to Hawaii, and shows up again along the Pacific coast in South America. It's usually a small, extremely prolific (it's all over my front yard), extremely evergreen plant. Does not lose any leaves in winter. Var gigantea is from a small area in Chile and is much larger than normal.
F. virginiana is widespread in the USA and Canada. I think it even naturally occurs within F. chiloensis territory. It is deciduous and very coldhardy. It was used to increase the coldhardiness of the hybrid.
Their more or less stable hybrid, the domesticated strawberry, has leaves that are typically neither entirely evergreen, nor usually entirely deciduous. It's sort of in-between ("semi-evergreen"). After a freeze it is likely to lose some older leaves. That might be what happened.