Hard to pinpoint what's off here in any given moment, and it isn't that it feels too different for the MCU. I went in expecting and wanting different. Maybe it's trying to mould itself into the MCU too readily, quips that don't land cluttering up a story that kind of needs to present itself more grandly than it's able to.
The actors don't sell it, only a couple feeling like they really believe the characters they're portraying. Throw in a frustrating ending that's hard to care about and you're left with something that's enjoyable enough but I can't really imagine watching again.