It shows error text as "Your app currently targets API level 27 and must target at least API level 29 to ensure it is built on the latest APIs optimized for security and performance. Change your app's target API level to at least 29. Learn More"
you need to change api level to 29 in buildozer.spec file
# (int) Target Android API, should be as high as possible. android.api = 29 # (int) Minimum API your APK will support. android.minapi = 21 # (int) Android SDK version to use android.sdk = 29 # (str) Android NDK version to use #android.ndk = 19b # (int) Android NDK API to use. This is the minimum API your app will support, it should usually match android.minapi. android.ndk_api = 21