Not sure what test you think you performed, but the little red LED, as you described it, is the IR illuminator. It isn’t really a tiny little red light, it is a huge, brilliant, glowing, super bright, LED, when viewed in infrared. We can’t do that, so we see just a tiny fraction of its full brightness.
Even with a phone cam, more sensitive to IR than our eyes, it can be seen to be hugely bright. No special tricks here, just a quick photo, in broad daylight, with my phone.
The source of this beacon of light, yes, you guessed it, the tiny little red LED. Tape over it, and the only night vision you will get is that which you could have got anyway with the IR illuminator in the off setting.
Here is my test taken in a cupboard, with the door shut, in a darkened room, with blackout curtains closed, to lessen the likelihood of any light getting through the crack in the cupboard door, which has a good seal anyway. Target object, my Jaguar cap:
The following photos are thumbnails, captured by the app, then downloaded direct from the Blink sever.
Thumbnail captured with IR set to auto.
Thumbnail captured with IR set to off. No ‘little’ red light.
Thumbnail captured with black tape over the tiny little red light, IR set to auto. See further photo to show location of tape.
Whist there is clearly a slight image with IR set to on, whist taped over, clearly I was blocking most of the IR light from the LED with the tape. Why might it work slightly? Some penetration through the tape is possible, not sure. We only know it is opaque to visible light, and don’t know its performance to IR light. Another possibility, the whole of the front of the camera is likely the same IR transparent colour, and there will be some bleed around of the IR, and we are super close to the target here, only around 18", so even the smallest amount of light will illuminate the scene sufficient for a dark image.
Do not tape over the little red LED. You will have no useful night vision. Only what you would have if you had the IR illuminator set to off.