Currently it only removes the 'know' transmogs but not the 'collected' transmogs.

We have 3 states of transmogs:
Uncollected:

Collected (missing filter):

Known:

the current version added a "learnable" which filters the last case like the "apperance: collected".

The "apperance collected: not collected" still shows collected appearances.

It seems to be a lot harder. even the newer code still has problems with some items not having appearances.

This addon fixed it by starting a dressup:
https://gitlab.com/toreltwiddler/CanIMogIt/-/blob/1bc7db82239ef53ce4ddede3cc2df0fde14979c8/code.lua#L970

I tried to improve transmog detection by relying on CanIMogIt if it is available, as using the base game API for transmog detection is not reliable in a lot of situations it seems. You need to combine the dressing room API with it to achieve reliable results, but instead of implementing it all in the addon I opted to add compatibility with CanIMogIt until I get more time to dig deeper in the default behavior.