The rating scale or EF scale for tornadoes is very very inexact science. In all honesty it’s the most flawed scale for weather/natural phenomena out there at the moment. Hurricanes can be directly measured I.e. pressure and wind speed, earthquakes as well are directly measured
and they’re all almost 100% of the time accurate. Tornadoes are so complex and nearly impossible to directly measure that we use damage alone to ‘estimate’ a tornadoes intensity. In doing so the true intensity of a tornado could be, and often times is, severely underrated just because it didn’t hit much or the structure it impacted wasn’t well-built enough and lowballed, even though winds may have been significantly higher in that location than the rating states. The closest thing we have to measure the strength of a tornado is dow however even with that it could be flawed as well, some examples of this include El Reno 2013 where winds topped 300mph in subvortices however vegetation, tree, and structure damage was no where near that of an EF5 also Rozel KS 2013 where winds were 185mph but again no damage was found that came close to EF4. Then you have tornadoes that may harbor over an open field for its life but contain winds of 300+mph and are capable of extreme damage but get rated much lower due to non structure impacts. It’s all very flawed and likely will be for quite some time unless some new invention or scale comes about.