NAT off on main router but second two routers will have NAT any Security Concerns?

This is what i've read somewhere ( Instead of turning off NAT on the main router, you may consider configuring the main router to pass through the necessary traffic to the two other routers without performing NAT on it. This way, you can avoid the security concerns associated with turning off NAT while still allowing the two other routers to handle NAT for their respective networks. ) Would this be a good Idea as I dont want double NAT and hence ~I would like to turn off NAT on the Main router and the second router will do NAT will their be any security concerns? The second router will be used

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