Firstly, if you are using bluetooth headphones, please be aware that bluetooth, the technology itself, adds a lot of latency. This isn’t an issue with Koala, it’s an issue with Bluetooth. Open any other app on your phone, you will see the same problem. Pls feel free to read more about this here: https://www.koalasampler.com/help/audio-interfaces/the-sound-is-delayed-with-my-bluetooth-headphones-speakers/
Secondly, android audio latency isn’t always great, it’s getting better but there’s still a long way to go. Just check these graphs. Bottom line is, Android phone manufacturers don’t care about selling you devices with low latency audio, all they care about is GB of RAM and HD screens, not about the actual experience (the one exception is the google pixel range) Huaweis are the worst in this list (160ms!!!).