Translation: "Why did I ever create Ukraine?"
I had a number of ideas about who might have droned the Kremlin, see 6 below, but I probably was wrong, see explanation after the 6 ideas.
1) Highly unlikely Zelenskyy ordered this done. Too risky with everyone chattering nukes. US and NATO would not approve.
2) Prigozhin or other faithful Wagners. A distinct possibility, it does appear Putin or his military elite have minimized help to Wagner and he is an ambitious man.
3) Disgusted oligarch business people who want to return to normal business and can afford experienced assassins and Drone operators.
4) Disgruntled FSB people if there is any truth to the info. from the FSB officer who has fled to Turkey.
5) Angry Chechen military being killed in Ukraine, including their current leader who seemed fearful when he last met with Putin.
6) Medvedev, who is being very vocal about Zelenskyy being guilty, who might profit from the end of Putin.
After writing the above, I found video which showed the small explosion against the flag on the Kremlin dome. The sound was hard to hear but apparently there was some disagreement within Russia over which was the right flag to display for the May 9 event. So probably domestic argument and no strong explosion meant to damage anything.