Commercial advertisements have been removed from the exterior walls of shopping malls in many places and public welfare posters by scientists such as Qian Xuesen and Deng Jiaxian have been hung. What are the possible considerations behind this?

多地商场外墙撤下商业广告，挂上钱学森、邓稼先等多名科学家公益海报，这么做背后可能有哪些考量？

A public trend signal observed across 1 source.