I want to try modifying the apk and when I try to build then install there is no problem, but when I check the icon on the apk changes like the default Android icon and the app crashes. Likewise when I try when decompile, build, sign and install without modifying the contents.
the tools I use are apktool.
Trying to use JADX but error when decompile

adb logcatlook at it to understand what is going wrong. Also check the code for code that checks the app signature and integrity. May be the crash is performed intentionally because the signature is wrong? Jadx decompile errors are common, that is nothing unusual some byte code is extremely difficult to recompile to Java language. – Robert Jan 22 '23 at 12:11