Ok, changed from https://www.coindesk.com/business/2022/06/29/coinbase-is-rep.... Thanks!

IP addresses are publicly available in cryptocurrency networks, tied to rough geolocation, and ephemeral. Coinbase could have been collecting historical IP address logs of the networks as one idea

Photo and video files used to have lat-long in the meta-data; they still do, but most image hosts strip it now.

Twitter used to give the ability to include the poster’s approximate location with each update.

Yeah, but in this context they should be linked to crypto transactions somehow.

Well, one can put bitcoin addresses in photos or tweets.

> No idea how geo tracking data can be “fully sourced from online, publicly available data”.

First idea was data brokers, who sit on tons of data, including geolocation. But that's not publicly available so... Maybe the "public" part is used for parallel construction rather than giving away the true source?

My imagination can get pretty wild, but I can't even begin to imagine how they could do that without severely bending the definitions of "Coinbase user data" and "public sources" to the point of breaking.

IP address?

That would be Coinbase user data. It's definitely not on the blockchain.

You can keep track of the IP address that you hear first announce a transaction. If you have enough nodes logging this across the bitcoin network, and someone connects a node running on their personal compute to the network in order to initiate a transaction, then you can basically have the location data for the person who initiated that transaction.

(There's a whole bunch of caveats here, but that is how it would work at a high level)

Is that data actually tracked and available publicly?

I'm sure it is tracked by interested parties, but I doubt you would be able to find it publicly, because why go through the trouble of running a bunch of nodes just to give your special information away...

It can be done by seeing which crypto nodes propagate the transaction first.