From it's Telegram channel:

Hello,

At approximately 21:33 UTC July 26 2021, I have been hit with a cease & desist letter from a law firm repsenting Facebook. The letter was sent to one of my personal email address as well as Barinsta's public inbox (and as a result, it is published). In response, the source code has been taken down, and all promotional materials within my control has been adjusted to reflect the fact.

While I believe it is nearly impossible to fight a resourceful multinational firm and reinstate the app, we will still try to get as much resources as we could to navigate in this crisis.
At this dire moment, I ask you to do 1 thing: Please let others know what is happening here. Such bullying behaviour against a young university student is in no way excusable. Such bullying behaviour against many internet users is in no way excusable.

It has been an honour of a lifetime to serve as one of the main contributors of Barinsta. I am forever grateful for the countless supporters along the way.

Thank you & Best Regards,
Austin Huang https://austinhuang.me

The letter was posted in the Barinsta GitHub as a sadly notice of the end of the project.