Under Manjaro XFCE (Manjaro 19.0.2 Kyria) I have installed Android Studio version 3.6.1 and Spotify from the AUR. Spotify and the Android Emulator group together in the panel despite being distinct applications
I presume you are referring to the window buttons plugin with "grouping" enabled. If that's the case, the problem is with the underlying libwnck library. For the applications menu this report makes no sense (even if both were in the same category/group this would be acceptable as long as the group makes sense or the desktop files specify it that way).