I like Strava but don't use it to track my miles. Strava consistently reports more miles than my bike computer. On bike rides it's reasonable, +/- 5%, usually +.
On walks and hikes it's outrageous. Regularly, after a 2-3 mi hike the mileage Strava shows is 5-7 mi. When you look at the map there will be several "jumps" where it appears you jumped a quarter mile to a half mile then back. Adding considerable mileage.
I've seen explanations for this but it doesn't matter. The numbers are unreliable. I think my bike computer can be within +/- 1% if you measure your wheel circumference regularly. But +/- 2% is fine with me.
I track my mileage in a spreadsheet and do a weekly summary for "fun".