During the physical foundations event - I've experienced several crashes, that exit me back to the arena direct entrance, game won page, followed by awarding me a game loss after I join again. (example at 10:30 pm pst nov 23rd I went 2-1, crash, joined a new game, won, and had claim prizes for 2-2

Examples of crashes I've encountered:

elenda blocking a fulling leveled up kellan. just kicked me out of the game (11/23/24 at 10:30ish pst)

flamewake phoenix and other creatures with force to attack and having a planeswalker as an option - game wouldn't allow me to assign attackers, got hung up.

Casting bake into a pie on a bloodthirsty conqueror

All said and told - I'd imagine I had 3 crashes that probably cost me a win and about an equal number that were at a stage where I could not determine my chances or was losing anyways.

Because the crashes result in just the game ending and sending me to the reults screen I have no screenshots to provide exact situations or prove my case but I hope that this log provides something for you to parse.