Funny colors on the display?

So it's about the Huawei p20 lite, I've had the phone for a while now and I loaded it earlier. Then I went to my phone and went to WhatsApp suddenly all the colors were different, the font was suddenly white the button for shots was red, I thought first is istn error with WhatsApp but when I was in my normal menu, the apps looked different off and on some pictures were so pixels in different colors. Have it turned off and on now is alels wiederr normal but what was that?

That could all have been in negative colors. I guess your cellphone got it a mistake and it stayed that way.