I think it is clear that degrowth can not happen under a capitalist system and when talking about degrowth in it the ideas associated are ofte no more than buzzwords. What exactly does "ethical consumption" mean under capitalism for example.
Also the word degrowth is not proper, a economy can only decrease as long as it can provide necessary goods for citizens, when the popultation grows, the economy has to grow aswell.
I believe, that under communism we won't define ourselfs by our consumption and thus we can get rid of our artificial desires, that now plague our planet. I therefore think that what you describe as degrowth is not a problem in communism, but rather a consequence of it.