Does anyone know if Kato changed the electronics on the little white LED light boards for passenger cars sometime in the last 3-5 years?

I ask this question because even though I have installed probably 50-75 light kits over the years, the newer installs seem to be more flicker free than the old ones I did. I just recently started to run the first passenger cars I ever did and they flicker a lot more than my most recent installs.