Poelstra's inquiry sheds light on the nature of signatures within tapscript, pointing out that unlike ECDSA (Elliptic Curve Digital Signature Algorithm) signatures which can vary in size, tapscript signatures maintain a consistent size. Specifically, all signatures in tapscript are exactly 64 bytes, with the potential addition of an optional sighash byte. This detail underlines a fundamental difference between the signature mechanisms employed within different parts of the Bitcoin system, emphasizing the streamlined nature of tapscript's approach to handling cryptographic signatures.