I feel XG is flawed if looking as a standalone stat, although it's not a bad stat to suppliment an overall evaluation. They just need to be put into context.
It seems Ole tries to punish teams early and then control the game when we have a 2 goal lead. Some games are contrary to this, like Leicester or Burnley but that's because it doesn't always go to script.
When it does go to plan though, the fact that we are just managing the game and sitting on a good lead means we won't bother to huff and puff for a goal as much, making our XG lower.
I prefer to look at the fact that we no longer have a negative goal difference and its actually competitive with the likes of Arsenal or Chelsea.