"Companies have begun to use the term "On device processing" to put users at ease about being spied on.

People think this is better for their privacy, but it really is just a benefit for the company, why upload and process the information on a different server? It is costly and a hassle to run.

Much better to process the data into text on the device first, text is much easier to manage and make use of and takes up much less space.

It's not better for your privacy, these text transcripts contain more than enough data about you.