Not sure what you changed about this filter on the AH but it is currently returning a ton of stuff it shouldn’t.
A week ago it started behaving differently if you searched Uncollected under Battle Pets. It started showing pet-related items like the Leash and the Pet Bed - even though they were already in your collection.
Perhaps this week was a change to fix that because that isn’t happening anymore (great!) - but now, it seems to have broken several other searches.
If you search Uncollected for Consumables or Miscellaneous, previously it would list only things like toys and mounts that were not in your collection, but now it just lists all kinds of low quality random stuff that can’t be collected. It appears identical to if you have no filter on at all for those categories.
I’m not sure if there is an official description for what Uncollected means but I would have expected it to only include things that can be collected.