Tried to reproduce this, but it is not happening now. If it does, then I'll report the 3mf
EDIT: After post, the changes were considered and the cause was found. With 2mm XY support avoidance, it looks good, with 3mm XY avoidance it produces the strange behaviour. 2mm XY avoidance will do it for me, but it will be nice to know how one can influence this.
Roof_orientation_2mm_wall_avoidance.3mf Roof_orientation_3mm_wall_avoidance.3mf