Here are top 5 bugs that can potentially give you an advantage in the game. I would've given the first place to smoke abuse but it would most likely be something you already know about and technically this is more of an improper balancing issue than a bug so we skip it. These are far not the only bugs I know of but these are the most useful ones

Running speed is even more valuable than armor. Managing it correctly can significantly increase your chances of survival. However, this bug makes weight management somewhat irrelevant.

If you're carrying a heavy load, pick up a grenade launcher (RPG or AT4) and shoot it. This will make you lighter, increasing your running speed beyond what it was before firing.
However, picking up a primary, a grenade launcher, dying or resupplying will reset the speed boost.
Notice: Picking up grenades does not affect it.
Double speed boost: If you pick up two grenade launchers and fire both, your weight will drop to the minimum possible value, regardless of your loadout. This grants you the maximum possible speed. Combining this with a super-heavy support loadout is quite effective.

I'm not entirely sure, but my assumption is that when you fire, the game plays an animation of discarding an RPG. This animation is tied to the RPG itself, meaning it must remain in your inventory until the animation finishes. The developers likely aimed for realism by reducing your weight immediately after firing.
However, since the RPG is technically still in your inventory, the game doesn't recalculate weight normally. Instead, it simply subtracts the RPG's weight. Because weight is capped at a maximum value, picking up an RPG when already near the limit only increases it slightly. But when you fire, it decreases by the full weight of the grenade launcher, which is substantial.

Sometimes you just can't kill a bot fast enough. In situations like these you die if you don't use any advanced strategies to avoid being hit. This bug will give you a way to extend your lifetime and save your life.

Insurgents can't see you leaning to the side, so you can save your life by leaning. It is a REALLY hard bug to abuse so here are key points for using it:

• Do not sit. You lean much more while standing
  
• Lean to the opposite side to where they are gonna look. Otherwise they will "accidentally" hit you
  
• Close to mid range use only. They are too imprecise at long range
  
• Use only when you can't move at all. Otherwise just leave
  
• You must be constantly looking their way or the opposite. Otherwise you will appear pretty much the same way as if you didn't lean at all

Note: This does not change with the difficulty of the bots
This bug requires a lot more research but it can certainly expand the gameplay of movement.

(Script is used in the video to showcase the possible maximum you can get out of this)

Need more money? We all do. This little thing will give you a way to get more stuff at the beginning of the game.

If the game has not started yet, you can kill yourself with a kill command to drop utility and weapons. Since you respawn right after, you can get a lot of utility this way. If you try hard enough you can start with a double speed boost with a heavy loadout.

If you ever wanted to reach your friend quickly, this is a thing you'd like to know.

If you get stuck in a physics prop, you get teleported to the closest ally. Usability of this bug heavily depends on the map.
If you've got nobody to tp to, you die.

Here are more or less usable setups:

Note: for this bug to work a physics prop with player collision is required. The only maps I've found those on are: Sinjar, Ministry, Siege, Contact, District, Revolt, Dry canal.

This is that one bug that isn't that useful on conquer. Instead the only real pve use is outpost. Best way to hit bots' spawn point while not putting yourself into the danger.
Note: It only works on these types of walls so no you can't just climb everywhere