Every wallet is a glass box.
A wallet has to be funded by something, and the chain keeps that forever. Paste one you already use and read its trail the way anyone can.
Do not paste a fresh wallet here
This check asks this site's server to read the chain, so the server sees the address. That is fine for a wallet whose history is already public, and wrong for one you mean to keep apart. A crossing never sends its far wallet here: a wallet made in the app is new by construction, and looking a pasted one up is left to you.
What the check reads
The first transfer that ever reached the wallet, and the first that ever reached the wallet that sent it. Two steps of public history are enough to tie most new wallets to an old one.
It reads transfers of ETH and of USDG. Other tokens are ignored, because anyone can send a worthless token to any address. A wallet funded only from inside a contract call may show no funder here even though one exists.