Condensation in headlight

It perhaps does, but it's not completely unreasonable. Attempting to seal anything like that is a recipe for worse problems, for a component manufacturer.

The headlamp unit will almost certainly have some vents. Might be worth having a look around it, to see if they are in good shape. Automotive component designs I've worked on, have incorporated things like these Gore vents into them:

www.gore.com/products/categories/venting

Despite what perhaps others are maybe implying here, I wouldn't expect the headlamp to be completely "sealed".

Is it also possible something else has changed? Is there something near the headlamp under the bonnet, obstructing the vent(s)? Has maybe your vehicle "usage pattern" changed? e.g. shorter journeys so the headlamp internals are perhaps not heating quite so high from the bulb (headlamp heat would help to expel moisture)? Or maybe you're just parking the vehicle differently or in a different place, so the ventilation around the one headlamp is slightly different to the other?

I appreciate it wasn't perhaps doing it before and it's annoying and it's perhaps unusual for a RAV to do it, but it's not totally unexpected, as long as it's not "swimming" in water.