They replaced the air filters with spore related items (inhalers, spore blockers, iodine, etc.), you can't get them from the sewers anymore.
I've just cleaned it with 3 bloodhound dogs + the healer buff, but I've got zero.
This run I didn't get a boat pump either, which could be simply a coincidence, but given the new loot they might have reduced its drop rate even further (I can't tell this for sure).
The boat was already a pain to assemble, this update simply worsened things. It definitely makes the sewers a more useful place to loot after getting the boat, but if you don't still have the boat, it simply sucks.
The only silver lining I can find is that everyone in the middle of building the boat has the settlement unlocked, which means you can clear the highway. Plus, it resets every 2 days instead of 3 like the sewers, so I guess the highway could be a valid alternative for air filters from now on?