It‘s likely the result of columbine sawfly larva. They can strip the foliage very quickly, although it usually regrows from the base sooner or later.

https://hort.extension.wisc.edu/articles/common-columbine-pests-columbine-leafminer-and-columbine-sawfly/

look at the stems very close... and they may still be on the plant. .. if so ... they are the EXACT color of the leaves and stems ...

most plants can releaf.. and recover .. leave them be.. and see if they can ... [as sah said]

i dont think of Cs as long lived plants... i almost wonder if last years didnt die.. and you have some new seedlings .. which would be smaller as you note yours ...

you dont mention what kind you ha e.. but the foo foo ones.. often done come true from seed ... but genetics devolve to more plainer types ...

ken