I've been on at least five long flights since I turned on ADS-B Logging, and have not seen the weird box/diamond. Maybe the solution to this is to turn on ADS-B Logging?!
Yesterday's flight was very hazy (it was just a few hours before a cold front came through) and calm winds, yet it was still nice to be out flying. Based on my iFlyGPS, there were very few aircraft out flying and most of those were sticking close to the airports. I think for my 1 hour 45 minutes in the air only two aircraft came close enough to even think about.
Near Cleveland, Texas -- 2:03pm Apr 9 2020