Running

GPS time was a minute quicker.

On device time or Strava reported time?

Strava often ignores time where it thinks you were stopped, and by stopped it could mean "where the GPS lost signal for a bit". Is the "elapsed time" different from the reported time?

(The only way Strava will use the full GPS elapsed time is if you set the activity to be a "race".)

Also if you've ever been on the other side of parkrun you'll see that the events are run on a wing and a prayer. I've had my official parkrun time modified by huge amounts as the person running the stopwatch missed a few presses or pressed a few extra times, or the people handing out tokens forgot to give them to a few people, or a few finishers ducked out of the finish funnel before collecting a token, etc.