Okay, can you give an example?!
You can see these addresses from 2011, which were translated 13 years later.
1L8SXqb31Ry2dKPRaY19xddo9fcsvCKVYN
1EySSGtSVitbMZSQmhNobvTEPdmGSwpsjA
And these are wallets from the very beginning of 2009, when they were still giving 50 bitcoins for a block.
1CGT3Ywaa2upJfWtUtbXonDPNTfZPWqzmA
1MBBJBFEaYKHFZAeV7hQ7DWdu3aZktjzFH
13J8FkimCLQ2EnP1xRm7yHhpaZQa9H4p8E
18E5d2wQdAfutcXgziHZR71izLRyjSzGSX
1C4rE41Kox3jZbdJT9yatyh4H2fMxP8qmD
I doubt that a person found his software after 15 years. It is impossible. And considering that these are the initial blocks and possibly the addresses of Satoshi himself, but not for sure. But it is a huge blunder to transfer funds from these addresses.
I myself mined in 2009, at the very beginning through the satoshi application. But at that time I was just playing around, and the reward for each block was on a new address, save a private key or see at that time there was no such function in the application. Or maybe I didn't know, only wallet.dat was for saving your funds.
At that time I had 2 servers at home, I kept my websites on one, and launched pirated game servers on the other. And a friend told me about bitcoin, I don’t remember how much I mined, the software worked for a month, probably 1000btc and that was it. I just deleted the application later, I didn’t know what to do with these coins.
You can search more precisely and find even more addresses.
It's always possible (and even happened) that old software had bugs like bad RNG, making exploits viable more or less. More probable than secp being broken in secret (though not excluded).
I doubt it. From those addresses that transferred 50 btc, all this stuff won't work. Only if there is a vulnerability in that original application. There were no others at that time.
Yes, it looks like someone is moving funds from old addresses, likely related to keys that were generated earlier using the initial version of BC Core.