Either you changed the default color of the button using AWCC, or either you are running a game that switches the color of the button, like Diablo 4.

I am not using AWCC. I find out that factory reset temportarily change color of power button indicator back to default color. But it won't last forever. So the solid red or solid orange colour of the power button does not indicate an error ?

"So the solid red or solid orange colour of the power button does not indicate an error?"

No. The online AW3423DWF User's Guide page 10 shows all that the Power button has two states =

Blue = monitor on
Blinking white = In standby mode

Vanadiel is correct. Something you installed is changing the color.

Mine changes color to RED whenever I run Diablo 4, and I have not installed AWCC. It just does it whenever Diablo 4 is running.

There's no setting in Diablo 4 for it, so it's a mystery to me how it does it. But it does...

I do run SignalRGB to control my other RGB stuff, so maybe that does it but it's not listed under SignalRGB as a device...