As an Engineer, I regularly use the main battle tank and the infantry fighting vehicle, but I am only able to shoot at a jet or helicopter with the IFV lock-guided missile if the aircraft has been painted. The MBT and the IFV can both lock onto targets that have been painted when using the aim-guided missiles. The IFV tank has to make a decision whether to use lock-guided missiles or aim-guided missiles.
Otherwise, only the Anti-Air Tank can shoot at aircraft all of the time (the AAT can shoot at Ground Vehicles if they are painted, however their missiles do not do very much damage to heavily armored vehicles), as well as shoulder launched anti-air missiles. And, quite frankly, I believe that most helicopters and jets that I shoot down are not aware that is the Anti-Air Tank rather than the MBT or the IFV that I am using.
I was not previously aware that when my lock-on missile was fired at an enemy aircraft they had no flares defense against it. To say that they had no defense is inaccurate since being out of range or being too low prevented the lock-on missile from hitting. All good pilots know how to fly low or zoom out of range. In any event, lock-guided missiles from the IFV will no longer be able to bypass the flares defense. And that's a good thing.
In real battles, aircraft including fast-moving jets are always in danger from lock-guided missiles. They absolutely can be shot down by those missiles. Aim-guided missiles become lock-guided missiles when someone laser paints the target.
No clue if this happens in real life but it happens in Battlefield 6.