(_Sign target) ->
/usr/lib/mono/xbuild/Xamarin/Android/Xamarin.Android.Common.targets(2457,2): error ANDZA0000: W/zip (24714): copy of 'assemblies/Xamarin.Android.Support.Compat.dll' failed [..../Droid/App.Droid.csproj]
/usr/lib/mono/xbuild/Xamarin/Android/Xamarin.Android.Common.targets(2457,2): error ANDZA0000: zipalign: failed rewriting '..../Droid/obj/Debug/android/bin/com.example.app.apk' to 'bin/Debug//com.example.app-Signed.apk' [..../Droid/CentroForms.Droid.csproj]
Solution: delete apk files and run build.sh again
cd Droid/bin/Debug
rm *.apk
P.S. Today, 2021.03.23 it works without errors (after Android SDK update).
Mono: 6.12.0.122 VS Code: 1.54.2 Android/Sdk/build-tools/29.0.2/