Tuesday was a typical day in the life of President Biden.

First, he did something incomprehensibly stupid by presenting an elderly Vietnam War veteran hero with the Medal of Honor without wearing a protective face mask — despite his wife, first lady Jill Biden, currently being infected with COVID.

Incredibly, he did this just minutes after White House press secretary Karine Jean-Pierre had told reporters that the president would be “wearing a mask indoors and while around people in alignment with CDC guidance.”

And Biden did it despite knowing that the Medal of Honor recipient, retired Army Capt. Larry Taylor, is 81, and therefore at a very vulnerable, at-risk age should he get the deadly virus.

That was bad enough.

But then he also did something incomprehensibly insensitive by leaving the ceremony before it finished, without waiting to hear the moving benediction read by Chaplain Brig. Gen. William Green Jr.

Other military veterans were understandably upset by what they saw as a shockingly disrespectful act.

“Pardon my French … But what a f—ing idiot,” raged former Navy SEAL and podcast host Shawn Ryan. “The continuous lack of respect Biden has for anyone is appalling. Hawaii, service members, active shooter victims, the list goes on.”

“At least he didn’t check his watch this time,” tweeted Rep. Wesley Hunt (R-Texas), an Army veteran, referencing when Biden glanced at his watch during a ceremony for 13 US troops killed in the August 2021 terror attack near Kabul airport in Afghanistan.

Both things Biden did yesterday were kind of jaw-dropping coming from America’s most powerful person.

Or they should have been.

Instead, I suspect most people just reacted like me and slowly shook their heads in weary bemusement that this guy is still running the world’s No. 1 superpower when he looks barely fit, either physically or cognitively, to run a bath.

I honestly look at Biden now and genuinely wonder if he knows what day it is, let alone what he’s supposed to be doing.

To say his behavior is alarmingly erratic is the understatement of the millennium.

It was no surprise to learn from a new book by The Atlantic’s Franklin Foer that Biden’s own aides treat him like a “toddler” because he makes so many gaffes that have to be swiftly walked back, like suggesting Vladimir Putin should be removed from power, and he admits to feeling tired from, Foer says, “physical decline and time’s dulling of mental faculties” and has very few public events before 10 a.m.

Let’s be honest, it’s no surprise to anyone, is it?

Even the vast majority of Democrats (69%, according to the latest polls) think he’s too old to be president, and the idea he might attempt to serve another four-year term in office is as mind-boggling as it is terrifying.

It’s not just the way he regularly stumbles down the steps of Air Force One, tumbles off bikes, falls flat on his face on stage — or just wanders around in an apparent daze much of the time that is most concerning.

No, it’s the way his brain just doesn’t seem to be functioning the way it used to, and how it desperately needs to for someone occupying the Oval Office and making endless life-or-death decisions.

As I wrote in June, I was particularly shocked when he recently ended a speech about gun control with the words: “God save the Queen, man.”

Why would he be saying that when my queen, Elizabeth II, died a year ago this Friday?

He was even at her funeral in London!

Biden’s shocking memory loss was as disconcerting as the time he asked during another speech, “Jackie, are you here?” as he searched the room for Jackie Walorski, an Indiana congresswoman who’d been killed in a car accident the month before, and whose death he’d acknowledged with a heartfelt public statement of condolence.

This isn’t normal behavior.

People don’t usually forget the deaths of those to whom they’ve recently paid personal tributes.

To do it once can be put down to a careless slip of the tongue, but to keep doing it is surely a sign of serious cognitive problems.

The sad, unnerving reality is that every time President Biden appears in public now, everyone — including his own White House staff — holds their breath to see what verbal mistake he’ll make, what vital US policy he might suddenly and dangerously rewrite, what indecipherable word salad he’ll spew, or just whether he can manage to stay on his own two feet.

As my Post colleague Michael Goodwin wrote Wednesday, it’s increasingly, painfully obvious that the Democrats should dump Biden as their 2024 nominee because even most Democrats don’t want him to run again, not least because they know the corruption scandals surrounding his son Hunter are moving ever closer to engulfing the president too.

I agree.

But I fear Joe Biden, like his probable Republican opponent Donald Trump, is way too stubborn, self-absorbed and power-hungry to just voluntarily walk away from what they both see as the best job on the planet.

He would have to be dragged kicking and screaming out of the race like the toddler his employees think he is.

So Americans have no option but to look on, with increasing despair, as the president of the United States further diminishes and degrades the greatest office of the land with every day that passes, every move he makes, and every utterance that comes out of his mouth.

What happened in the East Room of the White House yesterday wasn’t some anomaly.

It’s the new normal for President Biden, and things are only going to get worse as he ages and declines even more.

America deserves better than this unedifying, embarrassing farce.