I noticed that you can specify a level for creating a CKKS plaintext. My question is that suppose I have a ciphertext with a certain level, does it matter that it is multiplied or added with a CKKS plaintext with the same or different level? What is the recommended practice (and/or best performance) for specifying the level of a CKKS plaintext when doing ciphertext-plaintext addition or multiplication operations?
For efficiency reasons, it is recommended that you align the number of levels of the ciphertexts/plaintexts before performing an operation over them. This is done automatically (with the exception of the FIXEDMANUAL mode, where you have to manually ensure the scaling is the same). Encoding a plaintext (this holds for ciphertexts as well) directly at the level it has to be used instead at default 0 level saves both space since fewer limbs will be stored, and computation time since the dropping of levels does not need to be done anymore.
Thanks for the answer!