People are also touching their faces more often with masks, so spreading via surfaces becomes a factor. This virus can survive for 16 days on surfaces under certain circumstances.

But I also think that minor infections become more severe due to masks. The severe infections cause more spreading again.

The severity may be caused by recycling of the viruses via the cloth, the reduction of O2 and increase of CO2 reduce the strength of the immune system. Other factors: Less sunlight in face, less will to live (depression), reduced training of immune system.