Reduced χ² maps obtained for each target with the model parameters from Table 5. The vertical axis shows the mass-loss rate ($\dot{m}$) in log-scale, and the horizontal axis shows the temperature in linear scale. Higher χ² values are shown in yellow and lower values are in blue. Parts of the grids contain NaN values (white areas) where the model failed to converge to a physical solution. The minimum χ² value position is shown with a red cross, encircled by 1, 2, and 3σ contours in red and corresponding to our main model with a high H/He ratio (≥98/2, corresponding to model M1 in Sec. 5.1). The confidence intervals overplotted in gray show the best fits obtained with the same model but using a solar H/He ratio (90/10, corresponding to model M4 in Sect. 5.1) for comparison. Our estimation of the error that we used for the reduced χ² computation is detailed in Appendix F.3. We note the apparent correlation between $\dot{m}$ and T in the case of detections and tentative detections, which is further detailed in Sec. 6.1.