Presumably these buildings, mixed with the Greek UBs here.
View attachment 707734
Re: Swiss Flag
So, I modded a Hospital building into Civ VI a while ago and the issue is very familiar to me. As already mentioned, using a Red Cross icon is at the very least unethical. A Rod of Asclepius icon doesn't really stand out from far, it's more or less just a vertical line unless you a) use a high-res texture for the flag and b) are zoomed in to the max. The Caduceus is more recognizable from afar due to the wings, but is technically the wrong symbol and the game already does use it correctly for commerce.
In the end, I also settled on the solution Firaxis found (or stole from me, if I'm feeling full of myself
): an inverted red cross, i.e. the Swiss flag.
HOWEVER: There was one additional issue I had. Color. My Hospital building provides a mix of science and unit healing. I themed the building blue-ish through its glass facade. A frequent alternative to using the red cross is a
green cross. Unfortunately, red fit the HP-related bonus better. Green is the color of food and growth. But what's that? There is no more health or housing in VII. As seen with the Bath, health-themed buildings now seem to grant their bonuses to growth directly in the form of a Food yield. So green would be perfect!
tl;dr: use a green cross instead