Yes, for Fortigate HA one of the requirement is to have same physical connectivity. So if you have a 4 port LACP on one node, the other node also should have same LACP config. You need a separate LACP/group on switch. For example the LACP group to Node0 can be lag1 and LACP to Node1 need to be lag2.
This is to avoid sending traffic to backup node as part of LACP load balancing.
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