During combat, after blockers are declared, Arena used to stop before all damage to give priority to both players, and it still does if First Strike isn't involved. The issue however is that when a creature with First Strike attacks or blocks, Arena skips that stop and jumps directly to damage step, making it impossible to take an action before First Strike damage goes through. This has lost me multiple games of draft and is consistent enough that I feel safe in claiming it as a bug, even though I have no good way of showing proof as I wasn't recording my games.

Playing on PC on the Steam version of MTG Arena.