interesting, you're right they are devoid of warnings. I thought maybe it was an EU/Germany thing, but looking at American listings it's similar. This may be due to the level of UV-C exposure you're getting. EG weak laser pointers won't have the same caution signs as a Class IV laser.

Edit: Looking into it a bit more, seems that "far-UVC" light is a bit higher energy than the typical "UVC". It seems that far-UVC penetrates less deeply and critically is apparently much better absorbed by the dead layers of the skin than UVC, so it is currently recognized as safe... All I could find on it was a Columbia research artcle.