In October 2021, Helder Eijis published this formula for recovering the $y$-coordinate of an elliptic curve point from only the $x$-coordinate, the parity of the $y$-coordinate, and the curve's $b$-value, when the curve and co-ordinates are in the short Weierstrass representation (an operation generally needed when parsing compressed encodings of points on NIST curves):
$${y_P}'=\sqrt{{x_P}^3-3x_P+b_E}\\y_P={y_P}'\cdot {-1}^{{y_P}'+\tilde{y}_P}$$
Obviously, this is far easier to use in programming contexts than Nigel Smart's didactic "half-trace" process. But was it original? It was introduced without citation, only with the comment “ECC keys can be exported/imported in the SEC1 [sic] format”.
Is there prior art here, or was that formula invented for the first time in the development of that library?