Villagers don't seem to replenish trades. Unless it is intentional that they may run out of a resource indefinitely (nothing implies they do), I am unable to get them to restock. They have easy access to workstations. I see this issue mainly with the fishermen villagers (other trade professions do actually restock)

Villagers do reproduce and pick items up like normally (these were villagers generated before 1.14, if that helps).

Images are of one of the fishermen (whose trades have been locked for a while now and have yet to be restocked).