Apple Watch track detection inaccurate, showing wrong paths

For the past few weeks, my track workouts have been getting inaccurate. I use the Apple Watch's track detection feature to do 800m repeats. It started with it being off by like 10m some of the time, and since then it has gotten more frequent and worse. When I check the map of my most recent workout today, I see something very strange, my Apple Watch says that during one of the laps I cut through the grass. This has never happened before. I started doing my workouts on the track about 5 months ago, and there hadn't been any issues until now. Every workout until today the map shows perfect laps. I presume the track detection GPS is more accurate because it takes each GPS point and maps it to the closest point on the track, so it is less prone to GPS errors but somehow it made this mistake. I have already tried resetting the GPS calibration data yet it still happens.

[Edited by Moderator]