Falco Phantasm doesn't have a hitbox on Falco or doesn't have a hitbox for the last third or quarter of its travel unlike Fox Illusion. This means that Falco can be punished if he mis-spaces Falco Phantasm. Also, even with Fast Fire Bird, Falco is reliant on burst movements for horizontal travel which would get predictable and none of them are particularly powerful like Ganondorf's Dash Attack or Wizard's Foot or as versatile as Diddy's Monkey Flip. Falco can cover vertical distances fast, but his horizontal mobility is among the worst in the game which hurts his disadvantage as he falls fast and moves slowly in the air making juggles that much more painful compared to Fox who has a sex kick Nair to get out or Captain Falcon who is durable.
Usually, damage changes don't affect knockback, but this patch revamped Falco's Uair. Before the patch, if you hit with the legs, the sweet-spot, it killed Pit at 162% on the ground at center stage of FD on the 3DS. If you hit with the legs now, it kills Pit at 194%. That's a 32% difference. Oh, but it's on the ground, but it does make a difference. The patch basically made his Uair more like Captain Falcon's where you hit is where people get send and in this case, hitting with legs sends people diagonally. If you hit at the center or with Falco's body, they go straight up and that kills at 178%, a 16% difference.
Before the patch, Falco had two hitboxes on his Uair: his legs and his body. His legs had a lot of knockback and what you wanted to aim for juggles and kills while his body had low knockback which seems crappy, but Falco could use it to cause hit stun and confirm a Bair in the air or something like Down Smash on the ground. The body hitbox used to kill at 872% which didn't really mattered if you used it to confirm a Bair which kills at like 113%. Now, if you consider the center hit as the body hitbox, then it kills 694% earlier. Basically, Falco has a regular flip kick Uair like (Dr.) Mario, Luigi, Captain Falcon, ZSS, Kirby, and even Ganondorf. Personally, I would have preferred the old Uair since it killed way earlier and offered a hit confirm option. Also, Falco doesn't have the air mobilty to juggle well like Mario, Captain Falcon, or ZSS or the ability to confirm it consistently like Luigi with his D-throw or whatever Kirby does with his Uair. It could stayed as a wickedly powerful Uair like Ganondorf's.
Didn't Wolf do this, except with just Bair? Bair walls, bro. Hey, Seagull Joe! I found your new main until Wolf comes back!