c.b.a.a$b->onReceive points to an obfuscated part of your code. It appears with this cryptic name because you have enabled ProGuard in your Android project, which obfuscates the code. Obfuscation creates a mapping file as well that lists all the mappings that took place during the obfuscation. For instance, Class A -> x, Class B -> p, etc.
To find out to which line of code this error refers, you can do the following:
Go to Play Console and download the .aab file that Play Console mentions has a policy violation. (You can find it at Bundle Explorer)
After the file is downloaded, rename it and change its file type to .zip.
Open the zip file and navigate to a folder called BUNDLE-METADATA/com.android.tools.build.obfuscation/ and open the file proguard with VS Code, or just a text editor
Using the "Find" tool (Command+F), find to which class and method c.b.a.a$b->onReceive is mapped.