Just did the expanding foam trick outlined in the service bulletin. It does help. I still have sounds coming from the rear deck lid though. Not looking forward to taking that apart...

 

Just wanted to chime in, my 2020 max occasionally over harsh bumps had this same clacking noise, dealer never heard it. Funny went ahead and tried the strut bushing kit on both rear shocks, super easy to do and fixed my issue. Now what is odd is as others have mentioned, everything was tight, everything was installed correctly, and as I was doing it and checking for apparent issues I was expecting no change, but surprisingly all was well. Only issue I noticed was the metal sleeve had on each some bushing material stuck to it. Nothing offensive but that was literally the only difference I could see or find.