The game gives a player 75 seconds in which they can click and drag to make actions. Those actions are sent to the server immediately, and resolved (almost) instantenously. However, most actions have animations that take up a log more time.
For many actions, a player dows not need to wait for an animation to finish, they can just carry out the next action already. Since the server that actually runs the game does not spend time on animations (that’s client side only), those actions can be done.
The result of this is that even though a player cannot exceed their turn limit, it can appear that way to the opponent because the animations take up more time. And the opponent sees the next action only after the previous animation was finished.
(Have you ever seen an animation playing and whille that is still happening you see arrows dragged all over the board - and then after the animation all those arrows turn out to be queued up attacks - that is exactly what happens here, your opponent was actually attacking already when the arrows were shown, but your computer was still caught up in animating the previous action).
There is no bug, so there is nothing to fix.
If you ever find evidence of intentionally cheating (and again, the Priest combo is NOT cheating, it’s just someone playing very fast), then you can use the link below to find instructions on how to report that.