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The first science image released by the JWST reveals numerous galaxies in thedistant background of the galaxy cluster SMACS J0723.3-7327. Some have claimedredshifts of up to $z \simeq 20$, challenging standard cosmological models forstructure formation. Here, we present a lens model for SMACS J0723.3-7327anchored on five spectroscopically-confirmed systems at $1.38 \leq z \leq 2.21$that are multiply lensed, along with twelve other systems with proposed imagecounterparts sharing common colours, spectral energy distributions, andmorphological features, but having unknown redshifts. Constrained only by theirimage positions and, where available, redshifts, our lens model correctlyreproduces the positions and correctly predicts the morphologies and relativebrightnesses of all these image counterparts, as well as providinggeometrically-determined redshifts spanning $1.4 \lesssim z \lesssim 6.7$ forthe twelve candidate multiply-lensed galaxies lacking spectroscopicmeasurements. From this lens model, we create a lens finder map that definesregions over which galaxies beyond a certain redshift are predicted to bemultiply lensed. Applying this map to three galaxies claimed to be at $10\lesssim z \lesssim 20$, we find no image counterparts at locations (with anuncertainty of $\sim$$0.^{\prime\prime}5$) where they ought to be sufficientlymagnified to be detectable - suggesting instead that these galaxies lie at $z\lesssim 1.7-3.2$. In lieu of spectroscopy, the creation of reliable lensfinder maps for cluster fields are urgently needed to test and constrainredshifts inferred from photometry for a rapidly increasing number of candidatehigh-$z$ galaxies found with the JWST.

A Lens Finder Map to check claimed High-z Galaxies behind SMACS J0723.3-7327