You might remember this image from the debate. It's when the moderator asked who supported Medicare For All.

Sens. Bernie Sanders and Kamala Harris raised their hands at the second night of the first Democratic presidential debate when asked if they would abolish private health insurance, and the fraught politics of Medicare-for-all revealed themselves again.

It was a repeat of a question moderators asked the first night, when Sen. Elizabeth Warren and New York City Mayor Bill de Blasio said they wanted to end private coverage. Sanders and Harris said yes, which didn’t seem like a surprise: They are both sponsors of Sanders’s Medicare-for-all bill that would eliminate private insurance and move every American into a single national government insurance plan after a transition period.

So far so good.
She's a cosponsor of MFA and she got a straight question.

But after the debate, Harris said she interpreted the question to mean whether she, personally, would get rid of her own employer insurance to join a government plan. NBC’s Lester Holt set it up by noting many Americans — about half of them actually — get insurance through their job. But he actually asked: “Who here would abolish their private health insurance in favor of a government-run plan?” and that could arguably be interpreted as asking the candidates about their own insurance.

But does Harris actually support prohibiting private health insurance?

“No, I do not,” the California senator told MSNBC after the debate. She noted to CBS that Sanders’s bill allowed supplemental private insurance, though that coverage would be forbidden from covering most major medical care. Most treatment would be covered and paid for by a single government plan.

She was confused about the question?
This seems extremely unlikely.
Kamala Harris was the most over-prepared person on that stage.
Her "food fight" line was obviously tested with a panel beforehand, and that's not the most obvious example.

Harris herself ended up settling on a line that within minutes would appear in social media memes and just a few hours later would be screen printed on t-shirts selling for $29 on her website: “That little girl was me,” she said, of her desegregated class.

There was a little girl in California who was bussed to school. That little girl was me. #DemDebate pic.twitter.com/XKm2xP1MDH

— Kamala Harris (@KamalaHarris) June 28, 2019

So her campaign staff were ready to capitalize on her debate performance within minutes with t-shirts? That stretches credulity.
But the biggest tell is that this wasn't the first time she's made this "mistake".

It was also not the first time Harris had appeared to endorse a prohibition on private insurance only to try to clarify afterward. The same sequence of events played out during and after a CNN town hall in January — Harris initially seemed to support a more rigid version of Medicare-for-all, then later walked it back.

She "supports" MFA in public. She doesn't in private.
And she's done this twice. The most over-prepared person out there.
To say that this is unlikely is an understatement.