We haven’t had any complaints about battery drain on Android 12, I am suspecting that it has something to do with Android 13, you should probably contact Google about this.
If you are looking for another solution that is more battery friendly, we recommend using Blokada 6.
Blokada 5 runs filtering locally on the phone but on the other hand Blokada 6 connects your device to the cloud server, read more about it here: What is Blokada Cloud?