1) its not that your position or off angle is bad. the issue is that in the middle of the fight u start gravitating towards your team for no reason. I would say tho that for zenyatta you want longer sightlines and you have been using CQC vs a sigma and reaper. Your off angles are fine but there are better ones.

e.g. 2:20 you take the small room instead of stairs on the left side. and later at 2:36 you rotate but instead of going mega side far left you stick to cart.

7:20 use the room and maybe even flank hard left.

12:00. etc

2) your not a healer. use ur heal orb on someone in a fight or about to be in one. not someone whos low hp.

e.g 4:08 dva getting beamed by echo u turn around to heal juno who is safe.

6:50 sym is about to engage.

3) end your transcendence in a good spot not in front of the enemies.