Most early transactions including rewards for early blocks go to P2PK outputs and we don't know who owns them, Satoshi or others. In these output scripts (unlike the common ones today) we use the public key itself instead of its hash. Some people refer to this as being "less secure" which is both right and wrong.
When you spend from an address you are also revealing your public key. There are a lot of reused addresses in bitcoin. The whole security of asymmetric cryptography is that it is not only safe to reveal the public key but also by design you should do it.
Technically having the hash of the public key (unused P2PKH, P2WPKH, etc) instead of public key itself (reused address or P2PK) adds another layer of "safety", but it is incorrect to say P2PK outputs are less secure because security in this case doesn't have a degree. Bitcoin as a whole is either secure or it isn't. If some day a way is found to solve ECDLP within reasonable time (in simple terms to find private key from public key) Bitcoin becomes obsolete not just those outputs.