Damage Resistance is a bad concept anyway I'm not surprised they nuked it.
The soda popper's nerf was 100% justified and even now after the nerf it's still situationally better than scattergun.
The dead ringer nerf is one I'm kind of 50/50 on. They completely reworked it during gunmettle and I thought that the reworked version was more manageable than the previous while not being awful. But then they basically just re added all the damage resistance it had in a later update in addition to fire resistance and whatnot, which was a real head scratcher. I feel like people who complain about the dead ringer are excessively whiney and don't realize that it's the only equip that makes spy viable full time in pubs/highlander, because it allows him to get a kill and not instantly die for doing what every other class can. It's comparable to what the gunslinger does for engie. But at the same time, speed and damage resistance/health are two things you should never combo. Wish they fixed one of those aspects rather than ammo.