Why does the app need microphone access?
Only for voice address search. Speech recognition works offline, right on the phone: the recording is not sent anywhere and no internet is needed.
The Russian speech recognition model is bundled with the app and unpacked on first use. The microphone is on only while voice input is active and turns off right after recognition.
The permission is optional: refuse it, and all you lose is the ability to dictate an address instead of typing it.