Inspired by the comments on this question, why was Bagram Air Base abandoned so early in the withdrawal? It seems like the stampede of people trying to get out of Afghanistan would have been less chaotic with the airstrip at Bagram still in operation. Obviously we had to leave it eventually, but why was that done July 2nd rather than late August or early September?
The only relevant thing I could find in the press is that the Bagram closure date more or less coincided with the Pentagon announcing (on Jul 6) the watermark of withdrawing "more than 90% of its troops and equipment from Afghanistan". So it looks like from the Pentagon perspective [at the time] this closure wasn't early.
No plan survives contact with the enemy though, as the famous quote goes. And here by this I mean that clearly the Kabul situation took administration planners by surprise, as they sent thousands of US troops back in (around Aug 12), basically to substitute for the collapsed Afghan security forces around the Kabul airport. You can see this change on the declarative level as well:
National security adviser Jake Sullivan said Monday [August 16] that the “speed with which cities fell was much greater than anyone anticipated.”
On the other hand, when the Bagram airbase was being closed, the declarations were different:
“The jury is still out, but the likelihood there’s going to be the Taliban overrunning everything and owning the whole country is highly unlikely,” Biden said on July 8.