What are all those different localhost domains that apps connect to?

I'm using the Blokada adblocker on my phone, which acts as a vpn and can show me all the domains that apps request to connect to and let me switch them between an accept list and a deny list. Whenever I install an app with known trackers, I try to block as many of those domains as possible while keeping the base functionality of the app. I noticed that my log has about a hundred of domains with localhost in the name, many of them not even looking like a url. For example, among some that my phone tried to contact hundreds on times: localhost_name localhost0#3} localhostfo localhostz\012({ localhostsys localhost_code localhostdn.com localhostgs localhostsysu localhostms localhostal.org localhostp.net localhostde localhostt.com localhost.com localhostx.com localhostahn.de localhoste.com localhost=tun0 Some look like actual domain urls accessible on the internet, some not. Some have those weird special characters in them. What are they? Actual domains? Or are they pointing to a webserver running on my phone like normal localhost would? Why are there so many of them? My instinct was to block them on sight because I don't want apps to keep track of my phone connecting to their servers from different IPs, effectively mapping out everywhere I'm going. And I have a hard time trusting a domain name looking like "localhostz\012({". Is there a reason I shouldn't block them?