If you think that Liverpool had a 1.5 xG and united 1.52xG in that game and still think it's a stat worth anything at all then i don't know what to tell you.That’s a stat for showing the number of goals scored, but it’s not going to tell you how clinical a side were, which is what xG was created for.
Like I said, xG is mostly misinterpreted by people desperate to find a fault with it.