I’ve seen reports of artifact tracks on the day of flight, but not 2 days later!
You could try running an ADS-B performance report
https://adsbperformance.faa.gov/PAPRRequest.aspx
for both days and see what pops. Also check WAAS notams for both days, perhaps some anomaly there affected the ads b ground systems?
I’d be interested to find out what you learn.