Are you using the same device? A possible reason is with the increase in satellites and Garmin's ability to use more of them, it's recording your ride more accurately so, fewer 'blips' equals less distance recorded.
What does Google say the actual distance is? Maybe you weren't riding that 1km at all and now need to extend your commute. If it makes you feel any better, my commute is measured in metres now.
Firmware updates could impact phone accuracy (you'd hope for the better).
Are you using the same device? A possible reason is with the increase in satellites and Garmin's ability to use more of them, it's recording your ride more accurately so, fewer 'blips' equals less distance recorded.
Or you've found a shortcut or a wormhole.