Hi,
I see that you have the same description for all the other variants of your product.
So you probably want the same description for all of the variants.
In that case, please check that the description is entered in the main product, and under the "variants" tab of the product edit interface, edit the 120*180 variant and check that the description is empty.
That way, the system will automatically use the main product description.
I suppose that the issue you have right now is that the description is truncated in that variant only and that's why it displays truncated on the frontend only for that variant.