When you have a reputation for retreating from red lines and failing to appreciate that real problems need to be dealt with, enemies lose their fear and allies lose their confidence. Iraqis don't seem to think they can count on America:
The government has made it clear to Iran (which is very hostile to U.S. forces in Iraq) that some American troops were essential. The presence of American troops also makes it less likely that Iran will attempt anything too ambitious (like invading or backing a takeover by Shia militias) and everyone knows that. But now Iran appears to have convinced Iraqi leaders that American troops come and go while Iranian forces are always next door.
Most Iraqis are more worried about Iran than America, but the Iranians have a potent argument to make to Iraq's rulers: America is far and unreliable; and Iran is close and relentless.
It's tough for us to regain a reputation for being a reliable ally after squandering it in so many places.
I fear the price of restoring our reputation will be a bloody war--probably that doesn't even initially involve our forces--that nobody will see coming.