Apple Watch Pace Accuracy

I’ve been using an Apple Watch on my runs for about 4 years now. I has a S3 when I first started and never seemed to have any issues with it. My Apple Watch always read faster paces and longer distances than my Garmin did over the same routes (I ran with them both a couple times to check). I switched to an S7 this December hoping that it would have the most accurate GPS reading possible. However, my s7 is all over the board with accuracy. Some runs it will be pretty accurate while others it will be off by as much as a tenth of a mile per mile. The current pace readout lags behind the pace I’m actually running (ex. will read 5:10-5:20 when I’m jogging in between reps of a workout and 7:10-7:30 when I’m actually sprinting). The average mile pace also seems to be slow, especially for the first mile (ex. current pace will read 5:10-5:30 for majority of mile then the final mile time will read 6:45). When I upload to Strava, there is always a discrepancy (Strava reports significantly faster than the watch did).

What could be causing this? Is it a GPS error or is there a way to reset the watch or something? I mostly run on sidewalks and bike paths in open areas so there shouldn’t be a problem getting a signal.

I included a couple of pictures of the discrepancies between Strava and watch for reference. Thank you!