Found the line in strings of jelly.elf```echo "bitcoin: G9mzcaHrPAZnkfMCgsNrt5Y8VXSfV74E2kNhYeaWgPYCrtNDzZzC" > flag.txt```
We know Bitcoin addresses are written base58 and start with 0x80
Decoded the hash
```console➜ jelly echo G9mzcaHrPAZnkfMCgsNrt5Y8VXSfV74E2kNhYeaWgPYCrtNDzZzC | base58 -dflag{a70f5c001e67e4c26bf20dc457d43459}```