Yeah the results will vary with framerate but not by much in the common fps range. Noone may actually spot the difference, which is additionally “camouflaged” by non-linearity. So it may be acceptable to just go with it when you need to produce that eased feel.
I did a benchmark in one of the older threads where this problem was tangentially discussed. The convergence time gets longer on higher frame rates, and the difference is more pronounced for larger interpolation parameters: