A great many top US physics PhD programs have canceled their open houses with no plan to reschedule.
Some are intended on running "virtual open houses." Other's are just sending links to information that could be found on the internet regarding their program.
Is the April 15th requirement of a decision regarding accepting grad school offers of admission still ethical?
Is it reasonable to propose that April 15th be moved a month or two later?
A STEM PhD could take anywhere from 4-7 years in the US. That is a non-trivial amount of your life.