red indicator appears during video call or voice recorder

That red dot means that the microphone is active as it must be to make a call. Check this link...

About the orange and green indicators in your iPhone status bar - Apple Support

Sometimes the orange dot looks red...

katyutka wrote:

but in this case does it show an orange indicator? Does red mean that the phone is recording sound and video? is not it?

The dot will appear to be more red or more orange depending on display settings and background. But it means the same thing: your microphone is active. If your camera is active, you'll see a green dot.

It means the mic is being used.

no, it simply means that the microphone is on. Did your read the link?

Sometimes it looks orange; sometimes it looks red, but it's the same thing. It does not mean there is any recording going on (unless you're actually using a voice recording app).

Some describe it as Red and some as Orange. It’s the same indicator but people see it differently.