I didn't actually realize the numbers were that high for her... Ffs.
They know what they're doing. The elections in swing states are always down to razor margins. The right spoiler is almost a guaranteed win for the opponent :/
Third parties certainly know what effect they have. Their motivation is not to make the second party candidate win. Their motivation is to change the first party candidate.
According to Hotelling's Law, a two-party political system with FPTP voting results in candidates that are very similar. This is why the Democrats won't run real progressives for most offices, and why Sanders was forced out in 2016 with the excuse that he wasn't "electable" enough.
Third parties running for president aren't trying to win. They're trying to eat some of the votes on their side, thus pulling the main party candidates toward that third party candidate to reclaim those votes.
You can find others if you'd like to look, quite easily.
Edited to add the quote from Sawant:
We are not in a position to win the White House, but we do have a real opportunity to win something historic, we could deny Kamala Harris the state of Michigan. And the polls show that most likely Harris cannot win the election without Michigan.
Third parties help the democrats because the biggest third party is more right-aligned.
In Michigan Gary Johnson got 172,136 votes, in Pennsylvania he got 146,715, and in Wisconsin he got 106,674. If all Greens voted Clinton and all Libertarians voted Trump then New Mexico would've only been won by Clinton with around 1,000 votes, Colorado would've also been nearly Trump. Nevada, New Hampshire, and Minnesota would've been won by Trump. Maine might've gone majority Trump.