In inner layers set to planes, it is possible to generate isolated islands in the copper planes just as it is in Copper Areas in the top and Bottom layers.
For example:
![image.png](https://image.easyeda.com/pullimage/7n3gkyXp7W0u8brZWpb77VEoHplxizmmkOZyfJ02.png)
In Copper Areas there is the Keep Islands = Yes/No attribute:
![image.png](//image.easyeda.com/pullimage/hncDn2UZazcMJc3PuVa8VYSXn4w74oN8XJuB4AoU.png)
There is no such option available for inner layers set to planes.
Chrome
98.0.4758.102
Windows
10
EasyEDA
6.4.32