The key thing to remember about the displayed range remaining in your Tesla is, it is simply taking your battery charge and multiplying by the EPA estimate. Because other things affect how efficient your car is, the actual range left is most likely never going to be the same as the displayed range left. Cold weather, driving style, tire pressure, wind, elevation, extra weight in the car.. all of these affect how efficient your car is, thus causing deviations from EPA estimated range left vs. actual range left. Sometimes you can be more efficient too.
There will also be times, especially on Model 3 and Model Y vehicles, where the Battery Management System will become a bit out of sync. You can read a detailed technical explanation of why, and what to do to help resolve this, by clicking on this article or this one or this one.
As of the Tesla iOS and Android app version 4.11.2, you can actually get some diagnostics run to see if your battery needs service (per this link). Go to Service, Request Service, select Battery, then Range, then enter “loss of range” in the description. That prompts a self diagnostic.
Many people change their display to be percent battery left, not range (miles or kilometers) left, for precisely this reason. Note that the percent battery left is what’s probably not accurate, but this does hide the miles.