IQOS vs Cigarette filter study

One of the first things I noticed when switching from cigarettes to HNB is the filter does not change colour.
When I smoked cigarettes the filter started pure white and when I stubbed it out it had turned brown.
The white filter feels strange to a smoker.
It’s quite logical as there is no smoke in heatnotburn to discolour the filter.
Here is my “very unscientific” study with photo’s.

Here is an unsmoked cigarette filter:
and here is the filter after it has been smoked:

Here is the unused IQOS:

and here is the IQOS filter after it has been used:
The filter is the same colour.
Again, all quite logical as the heat not burn option produces no smoke. Hence no discolouration of the filter, but it just feels so wrong!

No, I didn’t smoke the cigarette in these photos.
I got a smoking friend to help me with it in his garden.