So your first common ancestors are your great great grandparents, so that’s third cousin, and they’re a generation older than you, so once removed. Third cousin once removed.

I believe that the answer is second cousin once removed.

I believe you need to count the distance to the common ancestor from the older generation of the two people being related.

I agree that the first common ancestor is OP’s great-great-grandparent. But only OP’s relation’s great-grandparent. So OP’s parent and OP’s relation are second cousins.

Then the removed takes you down the tree from OP’s parent to OP.