Is the app obsolete for Android ≥ 13? about pilfershushjammer

[kaputnikGo]

yes that is the question and has stalled development on this app.
The method this app uses to block mic access is to take advantage of the < 12 adherence to only a single user app being allowed access to the mic at a single time (probably due to technical but also legal wire tapping reasons). this has steadily eroded as more system updates made concurrent access the default, starting with voice assistants/recognition being able to listen in. There are ways of mitigating this, the Pilfershush app has a Omnibox/Assistant jammer function which is enabled via the settings, this spoofs the voice_recognition access and theoretically blocks other voice assistants from listening in.

Later android updates have added concurrent access which means that a lower priority audio app will get zero'd audio data (silence). this is vendor specific too. I think there is meant to be a flag that informs the losing app that it is now receiving zero'd audio but last time i looked it wasn't a requirement. So user information is limited.

Conversely the latter Android APIs are much better at informing the user when the mic is being used, reducing unused apps permissions and generally allowing more control. So for me the problem has moved from user apps to system apps, ie google. but as i use AOSP (Lineage) and FDroid that isnt really something that concerns me.

But I think that this app still functions as intended and can protect from user apps. But you should check the apps you have and the permissions they have.