Hi,
If you're in routed mode then you should not require NAT. Go to the configuration and do
a "show run group" you should see a group with the services in question and the VIP used
to NAT incoming request, just suspend the group and confirm load balancing still works.
If LB stops working that means your servers have a different/preferred L3 path to get to the client and that's why
Source NAT is in place.
HTH
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Pablo