My initial thought is “no,” since our eyes, being receivers for specific wavelengths of EM radiation, can’t see frequencies like infrared, no matter how bright. Likewise, my cell phone’s WiFi and cell modules don’t conflict with each other (as far as this layperson can tell, anyway).
But if, for example, infrared were sufficiently bright/energetic, could it affect neighboring frequencies, like reds?
It all depends on what you mean by affect. Two em waves in the same space will have a different overall amplitude at any frequency.
If you mean as in the overall color of light, that will change based on how much/what frequency waves are combined. Think about adding a bit of black sand to a jar of white sand – from a distance it will appear grey but the actual colors of individual grains of sand (frequency of “individual” em waves) won’t change.
For wifi, data transmission is via phase modulation of the em wave, so the signal is resilient against adding different frequencies/amplitudes but may suffer if the same frequency is transmitted at a different phase.
So to a sufficiently tuned and sensitive receiver, if I understand correctly, it would be trivial to distinguish between the two. That makes sense.