When topology is being fetched from the gateway (by running Get-Interfaces with Topology), network objects and a network group are automatically created for these interfaces.
These objects are used for interface Anti-Spoofing configuration, when the topology of the interface is defined as "Leads To Specific" and referring to the auto-created group.
The number of these objects depends on the size and complexity of the environment, but in some cases it can reach a large number of objects, making it difficult to search and manage them in the Object-Explorer.
Although these objects are not searchable in the object explorer they are visible in the network pickers through the application, as well when you search for them through API or through OPSEC applications that utilize API to communicate with Check Point management.
There is no issue to use this objects, however you need to understand that these objects are used in gateway anti-spoofing properties and you have to be careful not to cause traffic issues..