Steps to reproduce

1. Import a world or pack on iPhone using the workaround described in MCPE-47250.
2. Delete the world or pack from the world list or Settings>Storage inside Minecraft.
3. Navigate to Settings>General>iPhone Storage>Minecraft

Expected result

You do not find a copy of the world or pack there.

Observed result

The world or pack is shown in the list of internal storage along with various settings and cache files. It remains there after several restarts of the game. See demonstration here:
https://youtube.com/shorts/ALqzkY7RU1w?feature=share

Note: I was not able to reproduce this using the steps above on Windows, but I have previously found old copies of mcworld files in C:\Users\owner\AppData\Local\Packages\Microsoft.MinecraftUWP_8wekyb3d8bbwe\LocalCache\minecraftpe as described here.