How to safely seal Bathroom heatlamp vents?

My new build (fletchers) has heatlamps in the bathroom ceilings. These have lots of vents exposed to the attic. When I use the bathroom extraction fan, I can smell the attic air coming in (insulation).

Is there a solution to sealing this safely without causing an overheating fire hazard? Or does that require a replacement heatlamp that is designed to be sealed?

I guess sealing this could negatively pressure the house even more when using bathroom fans, but I have an ERV and was thinking of ducting the bathroom anyway.