Students using the same flawed online solution sheet as the grading TA

If the online sheet is incorrect and you suffered because of it, and if you have proof that the TA used that sheet, then you should point out to the professor of the course what has happened.

But, ask for a a comparison between your answers and those that the TA suggests. This will make it clear. The other students may suffer or not, but that is up to others. You have a right to a correct evaluation of your work and the professor should be made aware of online solutions - especially if they are incorrect and misleading students.

One set of students getting credit when they've broken rules and other students suffering when they have done the correct thing is the worst outcome possible.

You don't need to accuse anyone. Point out the online sheet. Point out the (matching) solution rubric. Show your own work and ask for a fair evaluation.

First and foremost, the issue here is that your correct answers were marked as incorrect, a manifest injustice. That must be rectified. Of course, the reasons why it was marked as incorrect are relevant, but do not let their legitimacy or otherwise distract from that basic fact. People marking work do sometimes make mistakes, even if competent. But that does not change the fact that you are entitled to have your work marked properly.

In your case, it sounds like the person marking your work got it badly and objectively wrong. You should use whatever appeal mechanism exists to have the work re-marked by someone else. If that does not rectify the unjustly low mark (and the unjustly high marks of others), you should complain higher up.

The first thing to do would be to convince the TA that indeed, he's made a mistake in grading. This includes all the examples you gave: that he has been using the wrong parallel inductance formula, that your approximations were better, etc. I would try to arrange a face-to-face meeting for this, since it's much easier to communicate your points then (especially since it sounds like you'll need to write formulae out).

If you manage to convince the TA I expect that he will sort out the rest, either by adjusting your grade up or adjusting everyone else's grade down.

As for the online solution sheet, there's a good chance the TA (and the professor) will be interested in knowing it exists, especially if it's being used by students & if it is incorrect. I would mention this too, but if he elects not to do anything about it it's not something to fight over. Your priority is to learn, and you're doing that; it's much less your concern if the other students aren't learning.