I am not misunderstanding it.

The non-fallacious usage of appeal to authority only applies to inductive reasoning; however inductive reasoning does not allow you to claim things with certainty.

And the core of this matter here is a bunch of muppets claiming things with certainty, about a topic that they cannot reliably know, and the claim turning out false, regardless of what the "ekspurrts" said.

(The same applies to any other genetic fallacy, including ad populum, ad hominem, etc.)

You shouldn’t take AtA being known as a fallacy as a reason to distrust authorities, or do some kind of ‘well I have to do my own, uneducated research on this subject.’

Emphasis mine. You're distorting what I said; refer to the fourth paragraph of the very comment that you're replying to. In simpler words, "you don't get to know after someone else's claim".

You shouldn’t take it as an automatic fallacy simply because the authority might have biases either.

It is automatically a fallacy as long as used to back up any sort of certainty (i.e. deductive reasoning). The conclusion itself might be true or false but it is not reliable.

At most you can use the authority of the claimer as a criterion for inductive reasoning; stronger if someone in the field, weaker if from a barely related field. That would be valid. But guess what - even with the best criteria, inductive reasoning still fails.

The key here is that an appeal to authority is fallacious when it’s stated to support a position that is not related, or the authority is not an authority in the subject.

• An argument from authority (argumentum ab auctoritate), also called an appeal to authority, or argumentum ad verecundiam, is a form of argument in which the opinion of an influential figure is used as evidence to support an argument.
• Description: Insisting that a claim is true simply because a valid authority or expert on the issue said it was true, without any other supporting evidence offered.
• appeal to authority // You said that because an authority thinks something, it must therefore be true.

The meaning conveyed by my usage of "appeal of authority" is aligned with the definitions within those three sites. What you're referring to would be a second fallacy.

And no, ‘There is a theoretical possibility the authority could have had a bias’ is not an acceptable reason to dismiss an expert opinion as a fallacy.

The possibility of authorities being wrong is so theoretical, but so theoretical, that you're commenting in a thread that doesn't exist! [/sarcasm]

Side notes / off-topic:

1. I'm not bothered by it myself but be aware that people in Lemmy are damn quick to catch this sort of "I assume that you're an ignorant, so let me enlighten you" discourse.
2. I'm almost sure that you're used to discuss fallacies based on the inane shit that Reddit says; be aware that that site works through insane troll logic, and fallacies there get all distorted (e.g. they call any sort of insult "ad hominem"). If that is correct, you might need to relearn this shit, seriously. Wikipedia is a good start.
3. I'm not sure on how much you know about inductive vs. deductive reasoning. I don't mind explaining this if you don't know it, but I'm not assuming that you're an ignorant right off the bat.