Systematic dispersion (standard deviation) σ_m across all epochs of NIRCam imaging as a function of observed magnitude for each band used in our analysis in section 4. The black dots represent compact (z < 0.4″) sources selected from the Weaver et al. (2024) UNCOVER catalog, chosen to be covered by each epoch. Image A is shown in blue, image B in red, and image C in green. A2744-QSO1 does not present photometric variability beyond the typical dispersion of objects in the catalog objects across all epochs.