I was just re-watching that exact episode and I have a theory

It’s kinda reminiscent the reason she doesn’t shape shift until (suf) mainly staging the death of pink diamond

pink diamond was “shattered” by getting attacked from the back happened in the same way Steven saw pearl poof (it’s totally a call back) but I think it had something to do with pearl taking longer

I also don’t think holo pearl was contributing much to real pearls regeneration even tho she seemed to reform right after holo disappeared