It is part of the deep web, just like Discord or any sites hosted on private companies intranets. Lemmy is not, you can just hit any instance with a web browser and view stuff.
To be completely clear, dark web/net and deep web are two different things. That wiki link you used is describing dark web stuff like tor etc.
I’ve replaced the pads on mine a couple times, the rubber on the thumb rest has a hole worn it it to the plastic, and the braided cable is all frayed and stuff. I’ve had the thing for the past 10 years at least. I know new ones are that cheap and that I should just get a new one at this point but the thing is just a workhorse.