If the door is severely deformed beyond repair, it is recommended to replace it. Or you can adjust the door hinge slightly. Most of the bumps are caused by baking paint on the MDF, but even if it is dry, there will be bumps. Unless you change another bulging board.
Extended data:
The door core of solid wood composite door is mostly made of pine, Chinese fir or imported filling materials, and the density board and solid wood veneer are pasted outside, hot pressed at high temperature and sealed with solid wood lines.
General high-grade solid wood composite doors, the door core is mostly high-quality white pine, and the surface is solid wood veneer. Because white pine is low in density, light in weight and easy to control moisture content, the finished door is light in weight and not easy to deform and crack. In addition, the solid wood composite door also has the characteristics of heat preservation, impact resistance and flame retardant, and the sound insulation effect is basically the same as that of the solid wood door.
References:
Baidu encyclopedia-compound door