No neither of these explanations is right. The paper talks about a specific type of model called an embedding model that produces vectors for datapoints that a

No neither of these explanations is right. The paper talks about a specific type of model called an embedding model that produces vectors for datapoints that are useful for downstream tasks. Normally you have to choose a single dimensionality for the vectors and store them all in a database that’s proportional to the size of those vectors. The method described is for a model that has multiple “options” for the lengths of its embeddings. You can use smaller vectors to save space but they don’t work quite as well. Paper analyzes this more in-depth.