What changes have occurred in the ranked match mode in Apex Legends and how has this affected the ranking system?

For season 21, the developers reverted to the old system: starting a match, you invest a certain amount of ranking points, but you get these points back for kills and high placement along with the opportunity to earn more. Details can be found in this video: https://www.youtube.com/watch?v=cjT4-mBqdLc.