Better understanding IPFS gateways

Hello, I’m new here.

I have a question about the IPFS public HTTP gateways: I understood that they’re regular IPFS nodes that cache the content they’re tasked to retrieve (according to here), but I’ve come across a situation where I have a hash (file uploaded through, I can retrieve the content via numerous gateways, yet ipfs dht findprovs doesn’t show any peerID. I haven’t been able to find a clear explanation about that (all I found is this post, but I don’t understand it very much). Are the HTTP gateways ‘special’ nodes that don’t advertise themselves on the DHT? or anything of the sort? If not then could someone please explain to me what it is that makes the gateway nodes ‘special’?

I found a related topic:

with the reply here (on GitHub) but I find that doesn’t quite applies to my question.