Loaded into the wrong match, then given a game loss.
I was taking part in a foundations quick draft, and loaded into my first game. I use a Saheeli Rai avatar, and when I began the game, my opponent Hagane was shown to have a Sheoldred avatar. However, upon entering the match, I was presented with an empty board, two completely different avatars, no options other than to play with my pet, who for some reason was sat in the middle of the board (see screenshot for evidence). The Teferi avatar said hello to me, but I couldn't return the favour. I navigated the reporting issues menu, and upon returning to Arena was returned to the Quick Draft start screen with a game loss. Given that I had not played a match, nor been given an opportunity to do so, I don't view this as particularly fair, especially on an experience that I paid 750 gems to partake in.

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DAC169#34537 commented
For compensation for Draft problems go to https://mtgarena-support.wizards.com/hc/en-us/requests/new/ and select "Report a problem with my event."