Tank Average Resetting mid Tank

For the second time now my tank average reading on the dash has reset unrelated to a fill up. One minute I'm at 18.1 and a few minutes later... 13 mpgs and it's changing quickly as it does with a freshly filled tank. Nothing else resets.

Any of you have this experience? The only thing remotely common both times is possibly gas sloshing violently in the tank. The first time it was an emergency stop on a downhill... and this time I had the truck off road, suspension twisted in a gully with the rear tire off the ground.

If that kind of thing does it though, you'd think it would happen often off road. That is why I'm asking if anyone else has noticed this. Thanks

 

https://www.tacomaworld.com/threads/resolved-t-sb-0148-16-uninitiated-trip-meters-reset.399689/

 

Saw that and posted there. Got my wrist slapped because it's not a trip reset. Just the tank average.