They have basic IR "filters" which are used to reduce IR light, but they don't totally block it, which is why you can see a purple light coming from TV remotes and such [0]
I just checked mine now, new Moto Play Z so pretty recent, and it's much less noticable than it used to be. However, going into a dark spot so nothing else could be seen, the led in the remote flashed a slight purple. Definitely enough to check it's working, but you need a bit more cover around it to be able to see it. In the past, they used to flash like bright bulbs.