Welcome! Thank you for your question.
A power of attorney is revocable at any time. The power of attorney that you are describing sounds like a limited power of attorney. It is pretty standard to have a limited power of attorney that is related to a specific real estate transaction. I am unable to confirm that it is in fact a limited power of attorney without seeing the document. However, based on your description it sounds like language from a limited power of attorney. If it is not limited then it would give the person the right to deal with all your finances until you revoke it instead of just the real property.
You also need to know that the limited power of attorney likely gives the agent the authority to sell the property even over your objection of the offer. If you trust them to not follow through with this authority then you can choose to sign anyway.
I cannot provide you with legal advise. I have provided you with information about the law related to your question. My answer, and any information that you find online, should not take the place of having a consultation with a lawyer in your area to advise you regarding your specific issues.
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