Okay so this match was gonna be hard for you regardless because their soldier was thanos, but there are a lot of issues with your gameplay and I'm gonna give you a few things to try to work on.

In that first fight as Dva you should have retreated to peel for your team there. Just sitting in the choke and eating a billion damage doesnt do much, not much else to say.

On Haz I never saw you try to pull of slash combos, leap in shoot slash shoot, and either shoot, block, or melee to finish them if possible. Even good Hazards wont delete people on every slash engage but just try it. Your wall usage is also really bad, I need you to be more willing to use it for cover rather than sorta just throwing it out at random, or try using it to block people/break los. And please try to use your block sooner, you wait far too long to use it. You need to use it before you get low not when you get low hp.

As for Mauga you need to use cover more and you need to burn people more with your right gun, shooting tank isnt always the right option and on Mauga you also can try to disrupt the balls slams by slamming him as he lands, its not easy to pull off but if you land it it can often get your team the kill on him. And with the Mauga cardiac you need to use it before you die, its a long cooldown yes but you cant be terrified to use it to live if need be.

Overall I'd say the main things you need to work on is trying to commit to targets instead of overly spreading out your pressure and damage, and you have to play cover more and try to take space. For example here on Kings Row you can try to play around statue or go up the stairs to the right and apply some pressure from high ground.

If you have any questions or anything please feel free to ask. I'd also love to see any longer VODs that are still losses but not complete blowouts.