@CompleatBeetthere's a book that could be written about about things that went wrong with bfn but I'll try and bring it down to a few key areas from my perspective.
1. The Formula: changing from garden warfare to an overwatch style was already going to be a deadly gambit (which didn't payoff in the end as we all see) and trying to blend newer mechanics with the game modes of garden warfare just doesn't work as shown with gnome bomb and turf alongside confusing fans who are unsure if the gane is a continuation of a spinoff with how much is taken over from gw. Removing variants was a death blow as no upgrades were going to replace the amount of variety they provided by changing how characters played, and we can see even popcap realized this with the introduction of legendary upgrades and their costumes (also if new characters and not variants were meant to be used then there was no reason to ever exclude torchwood and hovergoat from the game imo).
Maps, sprinting and broken spawns: the bfn maps are small and claustrophobic with little vertical options for attack or flanking unlike gw1&2 and sprinting had broken the flow of the game, "oh but they need sprinting because there's no teleporters", this is a flawed argument when you realize the spawn system puts you right outside of the enemy base and walking in takes less than 10 seconds and most of the areas you sprint in are basically filler where no combat happens in the first place (peachy district is a great example of this) alongside all classes moving at the same speed in sprint negating the need to pick smaller characters for faster movement speed or tank classes moving slower (imagine if the tf2 heavy and scout could move at the same speed, it would break the game and it does here).
The spawns are garbage on most maps as you now spawn too close to the enemy team and they can shoot into your spawn and supress you with no cover to take (payload maps are the worst offenders of the new overwatch style spawn areas) normal turf is a bit better where spawns are pushed back and classes can take cover (driftwood shores, main street, and zombopolis usually had good starting attacking and defending spawn distamces with cover and kill zones so the enemy could not get free kills on spawning enemy teams). Non turf maps became a nightmare with sprinting breaking the spawns on maps where teams could safely spawn in without being harassed and was why the team limit was reduced to 8v8 because 12v12 team vanquish is ridiculous and popcap knew it.
The new class design doesn't work: Scientist is the golden child when it comes to this being able to heal his team, himself, and easily escape from or get closer to oppenents with no delay to annihilate his opponents (it got worse with steam blaster) while in garden warfare he had to sacrifice damage for healing capability and vice versa.
Engineer is another example by being able to hit opponents he cant even see with high damage (just play one match of turning point and see how easily this is abused. He can stun his opponents for an advantage in a fight, have an aimbot ally that constantly reload for his and his team, and a speed boost that makes it even easier to run away from battle with sprinting.
Chomper a melee class can snipe better than snipers enough said.
Tv head and wildflower: why do these two have a melee attack almost as damaging as chompers? Oh boy, classes that get stronger when you stack them in class-team based shooter how could this possibly go wrong?
Superbrainz: his shield does not work at blocking damage, why does turbo twister exist, and why did popcap think giving him a short range flying first would help him in gnome bomb where he is undoubtedly the worst carrier in the gamemode.
Imp:besides looking like he got hit by truck imp also got hit by the nerf truck in bfn as gravity grenade is easily escapeable and small and impkata needs to ramp up damage over time with a clear indicator of how far away a plant will need to be to be safe. Zmech looks like garbage and plays like it to as popcap had to add sprinting for how bad this thing is in damage and the fact that imo doesnt even die when its destroyed means a plant can nearly be killed, win, and then be killed by a full health imp.
Rose: able to goatify opponents through walls with little resistance and thorn apart charges with time so you dont even need to play support to reap the benefits of its damage.
All star: a huge shield that is easily focused and destroyed quickly from the inside alongside buggy abilities.
Citron: discount reinhart with a gun and stun.
Corn: relies heavily on butter beacon to deal decent damage.
Wizard:homing attacks with high damage, wall hacks with little effort required, and a highly precise weapon.
Snapdragon: blue blazes kills from a country away, flames dont kill for whatever reason, and ability to attack from range and up close (electric slides electricity can kill, why not fire)?
Acorn and space cadet: hey imp why do you and z mech even exist again when these two are practically better in every way?
80s action hero: press trigger 3 times then pray your ability doesn't bug out and delete your enemy as basically a superior deadbeard or just press Y and nuke the area for no real downside.
I'm tired of typing so next section.
PVE half in the bag: gonna be honest some good ideas but the replayablity suffers and some of the missions and bosses aren't really that memorable from a gameplay standpoint with a repetitbe format for all 4 times through and the worldbuilding just feels disconnected and random (dreadwoods cool though).
The advertising: releasing and advertising a game on the same day with no hype or buildup "WHAT COULD POSSIBLY GO WRONG!"-popcap/ea probably.
Game modes: no new modes except battle arena and the mechanics feel worse such as sprinting killing gnome bomb and the way bases are defended in turf is abusable and encourages invisible nightcaps. Ops is a shell of itself and is way too easy. Weekly modes werent unique on the level of boss hunt, CVD, capture the taco, and some didnt even work when they were released.
Bugs, glitches, unfinished animations, and technical errors galore: even upon moving camera angles things in bfn would dissapear and reappear even on the characters designs (superbrainz cape, peashooters leaf, slides boot jet flames, and etc.) Reload animations were garbage in bfn as imp never properly reloaded, all stars rotors don't spin, corn didnt eject husks, engineer doesn't remove his clip and just smacks his gun, soldier is broing and generic, cadets robot wouldn't spin, sunflower wouldn't look up, and oaks sap reap ruins his reload animations and dont work properly.
Ive fallen through the maps at time.
Sound design is really badly synced with delays or audio not fitting the animations (scientists pain grunts on dance taunts).
The future: the game isnt likely coming back as the steam port massively underperformed and the game overall sold poorly.
