Are water drainage slots necessary in PVC windows?

Hello, can someone tell me if these water drainage slots in the PVC windows are necessary? I want to build a new house and the lower frame will be mostly covered by the facing brickwork. This would also leave no space for the slots. Maybe the new windows don’t have these slots either? Can someone help me?

In the windows known to me and installed, these "slots" are so-called "cleaning openings." When cleaning the inner frame, water should be able to drain out of the frame there. However, I also observed that rainwater during driving rain gets directly onto the glass into the frame and then harmlessly escapes to the outside through the openings. In my opinion, sealing them would likely cause problems.