Meta sells the same model at two prices, and the cheap one is paid for with your prompts
Meta lists Muse Spark 1.3 twice[1]. The standard model id is muse-spark-1.3 and the other is muse-spark-1.3-contributor[1]. It is the same model, with the same 1 million token context[1].
Per million tokens, the standard tier is $1.25 input, $0.15 cached input and $4.25 output[1]. The contributor tier is $0.10, $0.002 and $0.20[1]. Input drops to about a twelfth, output to about a twenty-first, and a cache read to a seventy-fifth[1].
What is bought with the difference is stated on the page in six words: used to improve our products[1]. Sending a prompt on the contributor tier gives Meta permission to use it and the reply[1].
The weights are not released. Muse Spark 1.3 comes from Meta Superintelligence Labs and is reached through the Meta Model API, where both tiers sit on the same page[1].