Spectra of the 2021 flare (black) and the best-fitting models (the MCMC realisations with the minimum χ²) assuming that the flare’s continuum is a three-order polynomial. The meaning of the different colours are: magenta, the stellar continuum; blue, the flare’s continuum; red, the sum of the two continuum components; orange, the hydrogen (Hα and Hβ) VBELs; purple, the helium (He II λ4686 and He I λ5876) VBELs; and cyan, the sum of all components. The wavelength ranges affected by NELs (light grey shades) and telluric absorption lines (dark grey shades) were not included in the fitting. In this figure, however, we have only marked those affecting Hα, Hβ, and He II VBELs for clarity.