I'm on Unity 2019.4.26f1.
Textures generated with the Substance plugin are straight up wrong and don't even tile.
Here I'm comparing the output of a sbsar in unity project vs manual generation in substance player and then imported:

As you can see here, the generated material doesn't tile and it has a different scale than the working (manually imported) one.
Generated textures don't even line up with each other:

Here, the generated normal and height maps don't fit with eachother.
Differences between manually imported texture and sbsar generated one in Unity:

Performance overall is also atrocious.