With F- in an acidic solution you have the following equilibrium:
F- + H+ <--> HF
Since this decreases the amount of F- in solution, then for
PbF2 <--> Pb2+ + 2F-
will favor the forward reaction (because Le Chatelier's principle states that when you remove a product, the reaction will favor the production of more product).
In contrast, HCl, HBr, and HI all fully dissociate in solution, so none of the chloride, bromide, or iodide gets tied up by the acid.