Hi Srikanth,
No system doesnt set firming indicator to all planned order with types VP.
Infact, VP is a non convertible planned orders. If you check such planned orders, you will not find conversion indicator selected.
As mentioned by Caetano in above reply, there are multiple situation under which this planned order gets generated.
The firming of planned orders is based on MRP type (firming relevant) and planning time fence.
BR,
Rohit