I got this bug in a Stadium round where after mercy rezzed me (I was Mei), I became immortal and wouldn’t die even after the enemy team got me to 0 HP multiple times. I was unable to shoot or melee when I was bugged but I could still move around.
You can see the replay here: HFS3R6 (near the end of the round) My character did go back to normal when the next round started.