"How do I fight this vehicle?"
There are weakpoints, but the general advice is to not attack it from the front. It is durable there, and will not care about the shoulder fired missile or antitank dart, at least once or twice.

However, in closer range or if you have a good shot, the optic block can be hit to deal good damage.

It is also worth noting that the hull side is much easier to penetrate than the turret side, and the hull rear is usually a one or two hit kill with most antitank weapons.