Edit: Solved with Tank DLC changes
AI inside Vehicles is capable of aiming on targets outside vision and gun zeroing range.
Demonstration: https://youtu.be/9vCRSGZzQe4
This is being heavily exploited on Multiplayer servers (for over 2 years now) that involve Tank vs Ground Combat.
Also APFSDS-T rounds are capable of high penetration on unrealistic range (Faulty Penetration falloff).