Renewed expired subscription but only got 2 weeks worth of Apple Music?

My subscription expired in November 9th, and I renewed it today on the 28th. It let me keep listening to music and I could have still listened today without renewing, but I decided to cause I thought they’d cancel it soon any ways. I now paid $12 for a month of music, and it says it will bill me again on the 9th of December. Why does Apple do this?