FortiGate 6000 and 7000 incompatibilities and limitations
See the following links for information about FortiGate 6000 and 7000 limitations and incompatibilities with FortiOS 7.4.2 features.
Network Security 
Network Security
NOC & SOC Management
Enterprise Networking
Business Communications
Zero Trust Access 
Cloud Security 
Hybrid Cloud Security
Cloud Native Protection
Web Application / API Protection
SAAS Security
Security Operations 
SOC Platform
Advanced Threat Protection
Endpoint Security