Had it out 2 weeks ago at BWI. It's white, they leave it in the original box so it's well marked to not be mixed up. The regular one is silver. Easy to keep the 2 separate.I have not seen that. I'm not saying it didn't happen, but it is not what I have seen. More often they will bring an entire special plate, fully prepared, out to the person who needs it covered in plastic wrap.
It is slightly variable though, depending on the allergy. If it is breakfast and the allergy is shellfish, they might just say there's no shellfish served at breakfast (but you could still request a separate plate),but more or less they encourage the person to take food off the line.
At the other end, I have seen them provide a special plate with an entree off the allergen menu, WITH the allergen marker, same as you would get if you ate in a TS restaurant. (It looks like a large toothpick and says "allergy".)
Other times, they will simply prep a plate of fruit or something and have it waiting in the prep room, covered in plastic with that person's name on it.
Still other times, a chef will come in person and list off various options they can provide. This might be the case if the person has multiple allergies or is say, vegan +has an allergy.
It is a little variable in what the CL can/will do. It varies from hotel to hotel, and visit to visit at the same hotel over time.
every CL offerings vary for everything. Goes way beyond food and not just for allergies. Heck, just last week I saw that Poly does not provide real napkins where both CR, BWI and WL (among others I'm sure) give you real napkins with silverware sets rolled inside. I'm so used to that that every meal I sat down without silverware while at Poly. I'm spoiled to have it on the table. I've learned a lot by having conversations with the manager and discovered just how much option they are given to running their lounges. Lene obtained really nice clear cups to use for hot drinks (makes them look so pretty to see the layers for some beverages). She gets really excited to see them in use. No other CL has them. It was something the sought out. Why others haven't no idea. It was something important to her so she got them.
I'm sure there are some allergy needs that get so complex there is simply no way for the need to be met. I imagine those guests really struggle anywhere they go