It's kind of subtle but Pearl's/Garnet's reactions make sense in a 'wait.that's not supposed to be like that' way while Steven's/Amethyst's make sense in a 'huh, that's unusual' way. homeworldstevenuniversepearlgarnetcrystalgemsamethystperidotstevengemslapisyellowdiamondbluediamondwhitediamondpinkdiamondrosequartzjasperdiamondssapphire. It should also be mentioned that while Amethyst and Steven reacted with more confusion than anything, Pearl and Garnet (the ones who actually knew what Homeworld would have looked like before hand) reacted with shock/horror, which I think also indicates this was a post-rebellion development. Homeworld Gems - Rebecca Sugar, Ian Jones-Quartey, Erica Luttrell, Joe Johnston, and Hilary Florido (Vol.2/Ep.8) The Steven Universe Podcast.

My guess based on those is that it's at least something that's happened since after Pink left, meaning Homeworld's.damage was likely at after the rebellion. It's also possible that whatever's happened to Homeworld has been a 'recent' development, seeing as how Blue/Yellow reactions when they arrived being of almost silent embarrassment and especially Yellow doing that 'let's just get this over with' eye-squint thing. Homeworld may turned 'planet destroying' into something relatively routine, but somehow I doubt they ever would have intended to do it to their OWN center of society. It very much look like it had been unceremoniously torn apart, whereas something like the the proposed Earth Colony, while hollow and devoid of life, definitely seemed to have had a deliberate structure to it.

I think something went wrong on Homeworld, personally.

Homeworld steven universe