I bet, if they haven't already, some of the info stored by sites is how we interact with it. And I bet with AI you can pretty much fingerprint someone based on habits.
So even your alt accounts will know it's you.
Edit: why do you think Reddit made the big push for their own app? Engagement, time spent looking at a post, how fast you scroll past something, all useful metrics for ad revenue. And we know that ad companies like tracking us.
Any spooky shit comes after the systems are developed for ads.
I don't think AI is necessary. Reddit was able to find all my alt accounts pretty easily years back. Now I'm banned I can't even sign up without the new account being banned in a few days for trying to circumvent it.
Edit: LikelySounds to me like an IP and/or MAC address ban (MAC address is tied to motherboards IIRC). I got banned once from one of my old favorite games (PSO2) for mistakenly swapping my vpn mid game. After a lot of troubleshooting and an apartment move in between, a MAC spoofing program is what did the trick.
Side note, does lemmy use markdown format? If not, does anyone know what it uses?
It isn't. It's tied to your network hardware, and can be randomised/changed at will (or at least, the one it sends out can be altered). Some phones do that when connecting, to make it harder to track them, for example.
If you're using an ethernet port on your motherboard, then it'd be tied to that, but if you're using Wi-Fi/Ethernet from a Network card, it'll be connected to the card.
I think it's a combination of IP address as well as app fingerprint when you login to multiple accounts within their app - they can see each account coming from the exact same app/device. I personally believe this was a HUGE part of killing off third party apps so they could collect a lot more data directly about you in their own app.
And IP factors in too. I was in hospital WiFi for a few days when my kid was born and got a random message on all of my accounts that I was banned for 7 days for "ban evasion". Never been banned before and had only posted on some parent subs during that time.
I think the IP address probably had bans associated with it given it was such a huge public network and was next door to a high school that used the hospital food court a lot too, and thus the WiFi also.