How Quartus estimate Routing Hotspots

I'm not sure what you're trying to achieve here. Routing hotspots are indicated based on the setting you selected when generating the routing utilization report in the Chip Planner (the slider where you choose what routing utilization you want to consider to be a hotspot aka the heat map).

Unless you are running into a no fit situation or you are having timing issues, you don't really need to be concerned with this. Is there a problem like this when you compile?

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