I don't think the lower volume level of the recent Disney releases is inherently a bad thing, it just goes against the grain by actually mastering to reference level and not bursting our eardrums at reference like most films lol. The problem comes when the dynamic range and LFE level are weak, even at reference volume. So IMO, actual reference volume is fine, crappy dynamic range and LFE level not fine.
That being said, I think the Infinity War audio is a little better than Black Panther or Thor: Ragnarok, still not what it should be though. My biggest gripe is the lack of IMAX aspect ratio! lol