then it’s likely that there isn’t an IR-Cut-Filter in the lens, which block IR light, in either the lens or in the camera.
As a result, IR light reaches the color pixels. As red pixels are generally more sensitive to IR light, red pixels receive an increase in photons.
The actual tint of pink depends on the sensor type, or more specifically on the quantum-efficiency of the sensor, which shows how the percentage of photons of the various wavelengths arrive at the sensor. For example 37% of the 820nm photos, 34% of 825nm, 32% of 830nm, 30% of the 835nm photons, etc.