My two front windows are double glazed white PVC, perfectly functional.
Except that, for reasons I will never fathom, they have this diagonal leading on them.
Same for me but vertical/horizontal lines. Must have cost more but no point to them – the house is a normal looking 50s built one and not some sort of mock tudor thing which might be the reason some do it.
I’ve had to tape the second one up to stop certain people leaving the loft light on for weeks at a time
Loft lights should be high up so only be reachable when up the ladder – or in the loft like mine.