The face of the person illuminated by the shelf flash in Canon 500D indoor is full of oil! ! What's going on here? Please ask the photographer for guidance!

It should be because the flash directly hit the subject's face, which is commonly known as the light is too hard. You can add a soft cover or box or reflective umbrella to the flash.

If it is an external flash, you can also adjust the irradiation direction of the flash to make it face the wall or ceiling (commonly known as jumping flash).

If the conditions do not allow, it can also have a good effect to tie a rubber band on the flash with one or two layers of paper towels, but attention will affect the white balance, so it is best to shoot raw format and adjust it later.