How a forgotten gpg-agent setting broke my KeePassXC SSH integration

Shortly after upgrading my workstation to Ubuntu 26.04 LTS, I noticed that my KeePassXC SSH agent integration had quietly stopped behaving the way it used to. The keys I store in KeePassXC, which I use in conjunction with git and SSH, were no longer being loaded and unloaded as I unlocked and locked its databases, so this was something I wanted to get to the bottom of.