I was paying $150 for the Startup plan since months. I had let's say 10K < profiles < 25K.
I checked by chance their pricing plan just recently (https://mixpanel.com/pricing/#people) and they increased the # of profiles included for free as a Mixpanel Partner (https://mixpanel.com/free/).
I was a bit disappointed since I also did not received any notice about this change.
I contacted the customer support that kindly downgraded my account.
So now I'm getting the same, but for free: $150/m saved.