I don't think the author here is particularly making the claim of a severe injustice. She also made no allegations of illegal behavior on Google's behalf.
I think the point she's articulating here is that she isn't a "typical" musician making profit from her music. She has hacked out a way to make money from her music that satisfies her fans and doesn't grate upon her own concious. Google has been a big part of that and now they are changing, perhaps for the better for most. But the change is unilateral and creates a personal problem for her.
Afterall, in the end she asks if anyone is starting a new streaming service, therefor leaving the implication that she is open to switch despite monetary detriment any such switch might cause.
Writing a synopsis from her perspective, I would sum up the article as, "Hey Google, I came here in the first place to circumvent the rigid and singular nature of doing business in the music industry "proper" and now you guys are injecting the same kind of problems into your own system. I have a hard time abiding that and I don't know what to do."
Google isn't obligated to meet her on arbitrarily chosen terms, so I don't really see the problem here.