From the outside looking in, it seems like Mixer had other factors that contributed to the decision to close up shop[1].
It seems like Phil Spencer had a meeting with the affected ex-employee but nothing came out of it[2].
Adding on to that, a leaked town hall video really painted a grim image of the company and the management internally.[3]
[1]https://twitter.com/MilanKLee/status/1274830702538821632
[2] https://twitter.com/MilanKLee/status/1286008870935179266