First of all, it should be noted that a legal person and its legal representative are different. A legal person refers to an enterprise or company, and its legal representative refers to the boss of the enterprise. We ordinary people often refer to the legal representative as a legal person, which is not rigorous. What you said is that there is no legal representative's signature on the power of attorney.

According to China's laws and legal practices, if it is the power of attorney of the legal representative, it is invalid without the signature of the legal representative. If it is a power of attorney of a legal person, the official seal of the legal person, the organization code certificate and business license of the legal person, and the identity certificate of the legal representative are all indispensable. So the entrustment you said is invalid.

The analysis is a bit evasive, but you can understand it through this.