Objects get a diagonal striped grey /white pattern

Ullstein's icon

I have not been able to find out under which circumstances an object suddenly gets a pattern of grey/white diagonal lines over it. It seems not to make any difference. The object still works but it looks different. Can anybody explain the meaning of this?
Many thanks

what does the grey/ white pattern mean?

Pedro Santos's icon
Ullstein's icon

thanks Pedro, got it.

Have a good day

HP