LDSS3 red optical spectrum of TOI-4336 A (black line), compared to its best-fit M4 template (Kesseli et al. 2017, magenta line). Spectra are normalized in the 7400–7500 Å region, and major absorption features are labeled, including regions of strong telluric absorption (⊕). The inset box shows a close-up of the region encompassing Hα (6563 Å) and Li I (6708 Å) features, neither of which is detected.