devtrackers.gg
It’s because the duel for some reason is programmed different. Your golems death killed the tower, but the golem should not have died there. The giant hit your tower winning the game for red, which triggers a death for every unit on the field. For some ungodly reason they didn’t just make it like the regular game so now your golem died, and the death explosion gave you a tower resulting in a false tie. You should’ve just lost but instead I’m guessing all that extra time you played was useless because the game was already over. It’s insane how bad they are at play testing since this would be such an obvious thing to check if you are changing the end game state check.
Edit: To answer some of the comments:
No, I don’t think that this is very easy to find nor do I think I would be better than they are necessarily. BUT, if you are changing how the game is ending, you would think you would check the case where unit dies dealing damage killing a tower.