Impact of different values of the effective collision strengths amongst the lowest ³F term in Ni III (see Table 3) on the lines at 7.35 μm and 11.00 μm in our reference model set. In the top row we show the DDT and MERGER models where these lines are largely overestimated. In the bottom row we show the GCD and DBLEDET models where the predicted strengths for both lines are comparable to those seen in SN 2021aefx (note the smaller ordinate range compared to the top row).