Whatever these apps doing in the background, it takes a lot of energy. That is probably one of the reasons why you can rent power packs literally everywhere in China.
Surprisingly, that not all of the reason, although push notifications does count. It's like Facebook's (Android) app (which famously tries to not remove something as much as possible due to bad app design), but much more heavier. This is why Chinese Android builds (without Google Services) has heavy-handed "battery optimizations" (more like killing apps).
So maybe it's not just the apps that make a difference, it could also be your location. Your battery can drain faster when your phone is searching more frequently for a cell signal.
And this can happen on trips because of the different local cellular operators and the different frequency bands used.
This is of course only a hypothesis.
This is mandatory in China?