End-user question about high-tier ISP packet loss

I am a typical end-user with a question best answered by this sub. Per sidebar it should be allowed as an educational topic.

 

Question: Who is responsible (legally and practically) for packet loss that occurs midway between my home network and a target server half way around the planet?

 

Example: I am located in Europe and connecting to a server in the USA. Specifically it's a gaming server located in a Chicago DC. I've been having connection issues and have concluded (after ruling out my home network first) that this is due to packet loss along the way, specifically at a Telia router (or is it a switch) in NY, where it's between a crazy 40-50% (other hops have PL at <1%). I suspect this is in NYC because of the hostname - nyk-bb4-link.telia.net. Whois is showing Telia's Swedish HQ address for all their hops (ffm, prs, nyk), so I am basing location info on the prefix. Also, I tried a couple other Chicago connections and PL is limited to Telia. msichicago.org was also giving me ~50% PL in nyk and 4% at ldn while chicago.gov and fieldmuseum.org had no PL as they were through seabone.net and att.net.

 

Of course I would like to get this connectivity issue fixed but more importantly, and that is why I am posting here, I would like to understand what is going on at these higher levels of networking. I get that my ISP is a member of a national IX and unless there's local peering going on (which in this case there probably isn't), then it's a question of ip transit, but which party is paying for that and who is responsible for the quality of traffic between my ISP and the target server? Is it my ISP or the gaming company that owns/rents the server in the Chicago DC? Do these IP transit clients usually have contracts with just one company? For example, if Telia transit fails, does the client have a fallback carrier and when/how does that kick in?

Basically, as you can tell, my understanding of this is very limited and I acknowledge the complexity of networking beyond that of my home, so if it's not feasible to provide an ELIx answer, is there at least a recommendation on some good reading material or even youtube channels that would help me find answers to these sort of questions? I came across "Tubes: A Journey to the Center of the Internet". It has a lot of reviews on goodreads, but an ok rating, so not sure if I should skip it for something better. For recommendation context, my current networking knowledge is an incoherent mess of wikipedia-level info (IXs, transit/peering, different tier ISPs, Colos, MMRs, Cross-connects, ASNs), so a book that would bring all that together and build on it would be mostly appreciated.