Flightaware tracking shows that airframe nowhere near there.
My guess would be bad position decoding. Not sure why though.
https://mode-s.org/decode/adsb/airborne-position.html
Once one bad position is calculated then it could be the case that relative position decoding is used assuming the previous known position.
Do you have a receiver range configured in the dump1090-fa settings?
I do not know nothing about receiver range setting in FA
My site is set up correctly and synchronized with about 300 other sites.
Marty
Ok i was mistaken. You could have mentioned the date of that “screenshot” 
It’s this flight:
https://flightaware.com/live/flight/N35271/history/20190228/2048ZZ/KPHL/KDEN
Looks like a malfunctioning transponder.
Date was 2/28/19 at 5:17 PM
I watched it on my site, and on the flight aware site also