That shitty moment when you are reverse engineering an app (LINE), but can't find any useful hints.
Web analysis didn't help. Decompiling the windows executable also didn't help. Testing the app on different behaviour with python scripts didn't help. Analysing the android app on windows with the jadx decompiler and other decompiler didn't help that much.
BUT today it worked. I did use a paid "Dex dump" android application. I found some methods that the app receives from the servers with a thrift protocol.
Now I just need to find the right parameters to be finally able to make a bot. Hehehe.

That was a hard way, but it paid out. I did learn so many things. It took me like a whole year.