Sudden GPS distance issues on same old routes?

Ive been running with Strava now for a while and have had no issues. I used it through my apple watch that recently died on me and so lately ive been running with it just tracking through my iphone. I do pretty much the same route every day down to the beach, some sections I always have spotty service but my data has always felt consistent. I run the same paths so often that I now have mental mile markers in my head but my last two runs my Strava has recorded my miles as much shorter than it usually does. Because the distance is shorter it’s also drastically sped up my pace as well making the whole run feel inaccurate.

Unsure of what to do or how to recalibrate since its the same app, same phone, same route. Im starting to train for my first half marathon so I really dont want to be cutting my mileage shorter than my plan is telling me to do.