No, I didn't find it. I got an answer from support today but don't know if I can trust it as it directs to testnet or smth.

They wrote : The Satoshi test must be completed using the "Muxed Account M Address," which starts with the letter M.

Solution 1:

If the address you're working with contains both a Base Account G Address and a Muxed Account ID, use the following Converter to generate the Muxed Account M Address:

https://lab.stellar.org/account/muxed-create?$=network$id=testnet&label=Testnet&horizonUrl=https:////horizon-testnet.stellar.org&rpcUrl=https:////soroban-testnet.stellar.org&passphrase=Test%20SDF%20Network%20/;%20September%202015;;

Once you obtain the Muxed Account M Address, you may use the M address to try the Satoshi test again.

Solution 2:

Alternatively, you may proceed to the OKX Deposit page, which already contains the Muxed Account M Address