Depending on the hash used, it could be subject to a length extension attack. That was one of the big engineering goals for SHA3, to not be susceptible to those

Depending on the hash used, it could be subject to a length extension attack. That was one of the big engineering goals for SHA3, to not be susceptible to those. https://en.wikipedia.org/wiki/Length_extension_attack https://en.wikipedia.org/wiki/Length_extension_attack