MacBook Air M1 black area on screen when hit by direct sunlight

I just bought my first Mac and I decided to get a MacBook air M1.

Yesterday I was using it in the balcony. The sun was shining directly on the screen. Still very usable.

After a bit, an area of the screen started to get quickly darker until it became almost black. I got scared and brought immediately the MacBook inside. Black mark was gone pretty quickly.

Now I'm wondering if this is normal.

Should I stop using the MacBook air under direct sunlight?