Powerful space laser detected by South African telescope
https://edition.cnn.com/2022/04/15/world/space-laser-megamaser-scn/index.html
When a far star causes something, the only way we can learn what happens to it is to observe light. So, as far as there is a limit of light speed, observation of far stars must be later than the time something happens to them.
But, breakthrough for solving the problem will be technically difficult.
