We present a JWST/NIRCam transmission spectrum from 3.9–5.0 μm of the recently-validated sub-Earth GJ341b (Rp = 0.92 R⊕, Teq = 540 K) orbiting a nearby bright M1 star (d = 10.4 pc, Kmag = 5.6). Using three independent pipelines to reduce data from three JWST visits, we find no evidence of an atmosphere. Null hypothesis tests show none of the pipelines' transmission spectra can rule out a flat line, though weak evidence for a Gaussian feature is seen in two spectra (2.3 and 2.9 σ). However, the candidate features are at different wavelengths (4.3 vs 4.7 μm), and retrieval analysis suggests they are not real astrophysical signals. Forward model analysis rules out a low mean molecular weight atmosphere (<350× solar metallicity) to at least 3σ, and disfavors CH4-dominated atmospheres at 1–3σ. Instead, the forward models find our transmission spectra consistent with no atmosphere, a hazy atmosphere, or an atmosphere with a species without prominent molecular bands (e.g., water-dominated). Our results emphasize the need for multiple transit observations and rigorous statistical tests to determine the robustness of molecular detections for small exoplanet atmospheres.We present a JWST/NIRCam transmission spectrum from 3.9–5.0 μm of the recently-validated sub-Earth GJ341b (Rp = 0.92 R⊕, Teq = 540 K) orbiting a nearby bright M1 star (d = 10.4 pc, Kmag = 5.6). Using three independent pipelines to reduce data from three JWST visits, we find no evidence of an atmosphere. Null hypothesis tests show none of the pipelines' transmission spectra can rule out a flat line, though weak evidence for a Gaussian feature is seen in two spectra (2.3 and 2.9 σ). However, the candidate features are at different wavelengths (4.3 vs 4.7 μm), and retrieval analysis suggests they are not real astrophysical signals. Forward model analysis rules out a low mean molecular weight atmosphere (<350× solar metallicity) to at least 3σ, and disfavors CH4-dominated atmospheres at 1–3σ. Instead, the forward models find our transmission spectra consistent with no atmosphere, a hazy atmosphere, or an atmosphere with a species without prominent molecular bands (e.g., water-dominated). Our results emphasize the need for multiple transit observations and rigorous statistical tests to determine the robustness of molecular detections for small exoplanet atmospheres.