You deployed a fully loaded FG-7121F in the data center and enabled sslvpn-load-balance.

You can use src-ip or dst-ip-dport on dp-load-distribution-method to make SSL VPN load balancing work as expected.

If an FPM goes down, SSL VPN IP pool IP addresses will be re-allocated to the remaining FPMs.

To have better traffic distribution you should use IP pools that increment in multiples of 12.

Enabling SSL VPN load balancing will clear the session table.