From a Forbes article in Feb 2023: "Netflix will have ways of knowing if you are still sharing your account with someone outside of your household. That’s because the streaming service collects a lot of data about you, including what you watch, where you watch it, the location of your home, and device IDs. This information can be used to ascertain whether it’s you watching or someone in another household.

Still catching up on this thread that is now 6 pages, so someone further up-thread may have addressed this already, but it sounds like some of you don't know that your IP location and your devices are logged by some websites and some companies.
Go to Google and type in "What's my IP address location" and go to the different sites it brings up to see what comes up. Some of these random sites will be eerily scary on being able to locate you, sometimes down to the neighborhood.

And if you didn't already know how to mask your IP address, it will list it. There are a couple tricks for doing this in your browser. Yet, this is why many people use VPN services, so their real locations and IP addresses can't be tracked.
Here is a photo from when I just accessed my Gmail account on 3 different devices (2 phones and my PC.) I did use my same wifi, so it listed the same IP address for each device, but it did say the different browsers, (Chrome & Firefox) I used and my
general location.
I tested out a couple VPN services a while back, had it mask and list me in Atlanta, or somewhere else. Then I logged into my Gmail and a couple other sites that I know are secure, after just having logged in from NYC 10 minutes earlier. Each account's security went NUTS and wouldn't let me log in, because there was no way I could suddenly be in Atlanta after logging in from my usual HOME location & IP address in NYC only 10 minutes before.

While, as a general rule, I don't like Big Brother tracking us, for these two sites, I was glad they are up on their security.