issue while plannign with MF50

Hello team

we are not using any scheduling for production order, schedule margin key is 900, GR and Production lead time is maintained as 0 Days in material master . We don't use any capacity planning.

But when I am running MRP production order/ planned order start date and end date is being scheduled. ideally start date end date should be same.

I mean the problem was appearing when we were loading forecast in MF50 but when we use Md61 everything is fine

Can you please advise what is needed to be done to stop capacity scheduling in MF50.