On coldcard on
Advanced -> View Identity, there's
extended master key fingerprint
I though this was the xpub from my seed, but even after I changed seeds, it remained the same.
What is it?
According to the answer below, the ColdCard will update the the fingerprint after you apply the passphrase. You can also save the passphrase to a SD to avoid entering it each time.
"You'll have to enter it in each time you restart the coldcard to access funds under that passphrase. Once you enter it and select "apply" it will update your fingerprint. You can also save the passphrase to a SD card which is encrypted and locked to that coldcard to avoid entering it each time." (link)
In the ColdCard official documentation, there is also this information:
"Press X to go back and adjust your passphrase if the fingerprint is not what you expected
Option to save encrypted Passphrase onto MicroSD
Press (1) to save your new passphrase onto a MicroSD card at this point. Your passphrase value will be encrypted and preserved on the card for next time." (link)
The extended master key fingerprint on the coldcard is indeed the xpub of your wallet. It's just that the first 10 letters or so are equal to every wallet, but the rest is different