This has already been answered correctly by
@Rocky_H.
The loss is substantial. It depends on many factors, many of which can be reduced. But it cannot be eliminated.
You have a 77.8kWh battery with the LR. The Performance has an 82.1kWh battery (typically only 81kWh available at the current time).
This is extremely well documented for 2021 vehicles; there is no doubt about it. You can take that 77.8kWh number as gospel (for your initial capacity). Your battery shows 353 rated miles at a full charge, which confirms that your battery actually has that capacity (this number WILL go down with time, and directly shows your capacity loss).
It's actually very well publicized in this forum, and we've taken great efforts to document it in the stickies for prospective owners. But certainly it is not well presented by Tesla.
One reason it is sort of acceptable, from a range perspective: These idle losses only add up in daily driving, when you're spending a great deal of time in park, and access to charging is frequent. They of course cost money, in energy, but they do not actually affect your range.
Take a road trip, and THEN take a look at the available energy. In that case, you'll find (when your car is new), that you have ~95.5% of that total energy (total energy 77.8kWh for you at the moment). So you'll see about 73.5 to 74kWh from 100% to 0% (with the remaining 4.5% of your energy, which you can use (it was used in the EPA test) but is not recommended, since you'll likely get stuck on the side of the road, being below 0%)
Your full charge energy is 353 rated miles, which is 77.8kWh;
there is definitely nothing wrong with your battery. Check the stickies for more info.
I'd expect on a typical road trip you'd get about 250 miles or so per full charge at 70-80mph freeway speeds. If you are driving much more slowly (50mph max speed), you might well see in excess of 300 miles. To get 353 miles of range from 100% to 0%, you MUST drive continuously, and you must see
about 210Wh/mi consumption. If you get 240Wh/mi consumption, your range will be about 310 miles.
If you drive at 20mph continuously (no stopping or starting) without any climate control use, I'd expect you'd see in excess of 500 miles of range. The record is over 600 miles for a RWD LR (with various other differences from the vehicles available today). Obviously that is never going to happen in normal use.
This doesn't exactly add up, but we'd have to know the exact distance traveled, and we'd need to know how much energy your car lost while sitting, when you were hiking. It actually seems like it might have been substantial - I estimate 5kWh (were you using Sentry mode at that time?). Did you spend any time sitting at the trailhead with the heat or the AC on? You basically have to check the % when you park, and when you get back to the car (and it's better to use rated miles since you'll get better resolution). Obviously all the % numbers have to be exactly correct to do these calculations accurately but they are quite deterministic (within about 1%) - as long as you remove all the losses when in park.
If you need further explanation, we're happy to explain here. You mostly seem upset, which I understand, but we're here to help describe what is actually happening with your car, and what to expect.
