It’s somewhat more nuanced than the image implies. Sauna is generally a place one uses nude, but even in Finland if you go to a public spa with unisex saunas, swimwear is to be used. If the saunas are separated and located in the gendered showering areas, like swimming centers, then swimwear is prohibited.

what’s that yellow acorn thing?

That acorn in Russian and Latvian saunas makes me feel awkward. The German word for penis tip is “Eichel”, literally “Acorn”

What’s blue-grey? No data?

Sit down in a sauna, look around, and say, “Wow, it’s like a sauna in here!”