Testnet 2 is a new test environment that allows operator nodes to try out various features that will be introduced in the mainnet later. One of the key advantages of Testnet 2 is the flexibility for operators to switch between Testnet and mainnet. The aim is to ensure that network performance runs smoothly without interruption before the mainnet launch.
In addition, Testnet 2 also introduces a very low transaction fee of 0.0000099 Pi, giving the community a clearer picture of the potential value of the Pi currency when full decentralization occurs, as quoted from the Pi Network website.