Ask HN: How are these AI cover songs made?

There's been a recent flurry of AI covers on Youtube and Instagram. For example: https://youtube.com/@fakemusicbr?si=G-RzKcm2iuXX56kI

Some of these songs are _really_ good. And pretty far ahead of where I thought audio AI was. Does anyone know what models and tools are used? I imagine once you have stems you can maybe style / genre transfer and use a reference audio file perhaps? Like image and video models.