I'm sorry, but this is on the developer / maintainer.

Google has been putting out these warning messages for a while, and any decent Android developer should know about target SDK versions.

Didn't test the app on the platform they were updating to?

Didn't function test the app on a physical device that surely had on hand?

Somehow this is Google's fault?

I dislike the stronghold Apple and Google have as much as anyone else, but this is just shoddy maintenance and you've effectively advertised that your "agile software company" can't update an app without proper process, lack the ability to keep on top of well-defined changes within Android app development, and to top it off have the gall to claim Google is being unprofessional?