In a way, sounds similar to what is going on in the motion/“Cine” world right now, with a lot of lens manufacturers releasing “soft” versions of their lenses, where they’re essentially messing with(even removing) the lens coatings, but they’re going for the whole image, not just the bokeh. Sigma’s ‘Classic’ Cine Primes just announced in the last several months are the same f-stop as their existing high-speed Cine Primes(most* are f/1.4 / T1.5) but because of the coating manipulation/differences, they are slower in actual light transmission, going from T1.5 to T2.5.
*14mm & 135 are slower at f/1.8 / T2 in standard high-speed version and go to f/1.8 / T3.2 in the soft versions.
20, 24, 28, 35, 40, 50, 85, 105 are all f/1.4 / T1.5 in standard versions