Justin Trudeau turns out to be even more of a vapid idiot than we’d thought. But what price will he pay for his idiocy?

Canada’s ultraprogressive prime minister stands exposed as having donned black- or brownface at least three times in his younger years — the most recent occasion apparently being in 2001, at age 29.

The first image to surface came from a private school’s “Arabian Nights” gala where Trudeau was also kitted out in turban and robe.

He apologized for that one Wednesday, then owned up to singing “Day O” in blackface at a high school talent show. (Apparently, no one was checking his old yearbooks until now.)

And Thursday, up popped an early ’90s video of Trudeau in blackface and an Afro wig.

He’s apologized: “I shouldn’t have done it. I should have known better, but I didn’t. And I’m really sorry.”

Of course, he can’t claim that, bad as it looks now, people didn’t see donning blackface as such an invariably, horribly racist sin back then: Too much of the left spent too many days last year demanding Megyn Kelly’s scalp simply because she’d made that observation — even though she never actually donned the offensive makeup.

She also apologized, on air and with tears — but still lost her job.

Then again, the rules seem to be different for liberal sinners: Virginia’s Democratic governor and lieutenant gov both held on after their younger-days blackface photos surfaced.

To us, this is mainly just fresh proof that Trudeau is a phony — a chameleon whose current perfect-PCness is a pose in pursuit of popularity and power. But is it worth his resignation? No. This scandal will simply be one more thing for Canadian voters to take into account in their coming elections, where polls already had him in trouble.

We can’t let “cancel culture” overtake all — shaming people for past actions to the point that they get kicked off social media or, worse, lose their jobs.

The greater sin is that many liberals use such tactics to get rid of those they don’t like, while fellow travelers get let off the hook. Will they be outraged equally and fairly, or turn such incidents into witch hunts? We already know the answer. You can win mercy when you generally say all the right (i.e., left) things and vote or govern accordingly. Otherwise …

Better to stop getting hung up on every tweet, every ill-advised costume, every long-ago foolishness and instead focus on what’s important: Who a person is today.