Because EAC injects code into the Far Cry 5 process, your antivirus sees it as a ransomware-like behavior.
Network & Packet Validation
Players frequently encounter errors such as "Easy Anti-Cheat not installed" or "Unrecognized game client". Standard fixes include: Easy Anti Cheat: Unrecognized Game Client (Easy Solution) far cry 5 anti cheat
The Far Cry 5 Anti-Cheat: A Robust Defense Against Malicious Gamers Because EAC injects code into the Far Cry