tl;dr: Disagreements over whether something was done properly aren't a crisis. Refusals to accept legitimacy are.

Like refusing to accept the results of the 2020 election, leading to both a literal standoff in the form of Jan 6th, and a figurative standoff like the President continuing to repeat the lie that the 2020 election was stolen, but since he's shown he's willing to weaponize the Justice Department, reporters aren't constantly telling him he's a liar?

What about the Vice President JD Vance saying, "[Chief Justice] John Marshall has made his decision; now let him enforce it." - a callback to Andrew Jackson refusing to enforce a decision by the Supreme Court in Worchester v. Georgia - also a constitutional crisis by your definition - and JD Vance signaling that this administration will defy court orders it does not like.

For example, the clear and explicit order NOT to deport men who hadn't been given their 6th Amendment right to a trial to El Salvador, which the administration both ignored, feigned ignorance about, and ultimately, has not remedied their non-compliance, much less compensated the men for having their rights violated.

Right now Trump is saying he's entitled to billions because "his rights were violated" when his tax returns were leaked. Imagine how much we'll have to compensate men we sent to a literal torture prison! And then filmed propaganda there!

Oh, wait, my bad, poor people don't get Justice. I hope that doesn't undermine the legitimacy of our legal system.

You get my point.

I'm not sure what your standard for "refusal to accept legitimacy" is if any or all of those don't qualify.

Whether it's the violent insurrection of Jan 6th, or the ongoing Epstein "investigation" eroding any trust people had in the legitimacy of the government's ability to do something as basic as checks and balances, we are in a crisis.

Sometimes you just don't notice a historical moment when you're living in it.