I personally have tried FB groups, for both birds and rats, and hated them every time. So many people with such mean and sometimes wrong opinions, often incapable of expressing themselves constructively without insulting the people who just wanted help!!! This forum has been much kinder to me over the years and I value the advice here.
As for covering the cage, I agree with GaleriaGila, different bird owners will put their birds to bed differently but cage covering is very common and even popular. It does protect birds from drafts at night or if they live by a window or air vent (although, if the location is cold 24/7 because of a window or air vent, you may consider moving it so that the blanket isn't necessary all day long).
As long as the front of the cage is not covered most of the day, and you have a cage with bars, not a tank or solid acrylic, respiratory issues won't be a problem most likely... and if you do have to see a vet for respiratory issues, you can talk about the cage at that time, rather than worry about unsolicited facebook advice!! That's what I say. And at night, birds do need darkness and quiet, and a LOT of people opt to use blankets over the cage to give them that unless they're able to close them in a separate room away from nighttime people activities.
Edit--also, I wonder what that random facebook user would say about my bird cages having a sheet on the back........ to protect my walls from projectile chop and bird poop!!! Ugh, people on facebook are needlessly mean.