Is there any feng shui effect on the flat slope of the master bedroom?

When you say that the floor in the bedroom is inclined, it shouldn't be very inclined. As long as it doesn't affect your daily life, Feng Shui is not a problem.

The bedroom is surrounded. Only the door is the entrance and exit of gas. Unless the indoor ground level inclines towards the door, and the inclination is very large, it will have an impact on the wealth of people in the room.