Barry Allen being the source of the Speed Force.
It just feels like a cheap gimmick to make him more important than all the other Flashes, not just for now (like Wally discovering new ways to use the Speed Force or Bart absorbing it), but forever. No one can ever be better than him, no one can ever surpass him, no one can really succeed him without being second-rate, because hey, being a Flash is all about Barry Allen!
It’s like two kids trying to one-up each other in a bidding war, and one pulls out, “well, I bid infinity!” When it’s a kid, you laugh at that sort of thing. When it’s the Chief Creative Officer of the company, it’s canon.