Facebook's updated community standards include a provision that ban the use of commonly sexual emojis or emoji strings.
While the standards don't explicitly say which emojis will be targeted, the eggplant and peach emojis will certainly be on the watch list.
However, to be banned, the emoji use must also implicitly or indirectly offer or ask for nude imagery, or sex or sexual partners, or sex chat conversations.
These emojis are not totally outlawed, just in specific contexts.
You can see the Facebook Community Standards for content here.