MIAMI — Losing can be painful enough, with the Miami Heat dealing with plenty over the past three weeks. Death by 3s can be excruciating.

As it was in the fourth quarter of Friday night’s loss to the Boston Celtics and then throughout the night on Sunday against the New York Knicks.

Lately, much of the pain for the Heat has been over the top.

Despite entering the week sixth in the NBA in 3-point defensive field-goal percentage, the Heat also entered the week allowing the seventh-most 3-pointers per game.

So, yes, there is acknowledgement that something has to change.

“That’s us,” guard Norman Powell said of opponents recently breaking open games three points at a time. “I mean, the Boston game, you break down and watch the film, everybody is like, ‘Oh, they just got hot.’ But they took advantage of our glitches, our miscommunications on switches.”

The Celtics were 10 of 15 on 3-pointers in that fourth quarter, on a night Boston guard Derrick White closed 9 of 14 from beyond the arc.

“The first half we did a really great job getting them in the mud, taking them off the three-point line, making their three-point shots tough,” Powell said of the loss at TD Garden. “And then I’ll say the last 15 minutes of that game, our miscues and miscommunications and switches on defense and that Boston game opened up the threes for them. And then they got hot. They burned us on every one of those miscommunications on defense.”

Fast forward then to Sunday night at Madison Square Garden, when the Knicks closed 20 of 38 from beyond the arc, with guard Mikal Bridges 6 of 7 on 3-pointers.

“Not getting back in transition or locating Bridges in transition, he got a lot of wide open shots there,” Powell said, with the Heat turning their attention to Tuesday night’s game against the Toronto Raptors at Kaseya Center, before a two-day Christmas break. “So, I mean, it’s honestly us and being more mentally locked in and knowing guys’ tendencies and what they like to do.”

The Heat’s approach has long been prioritizing protecting the paint, while also appreciating the need for energetic and timely closeouts at the 3-point arc.

But in what increasingly has evolved into a 3-point league, such daggers become defeating.

Guard Davion Mitchell said it was clear the Heat allowed the Knicks on Sunday to grow their confidence throughout the game from the arc.

“I think when you get comfortable and you kind of let them get open threes or threes that we should contest, and they hit one, you kind of get confidence,” he said. “Just like the beginning game, you get confidence. It’s kind of hard to stop any of those guys because they’re really good players. So I think we got to start at the beginning of the game and not making them comfortable.

“Make their first shot like a hard one or a tough one, a contested three or even just run them off the three-point line, and kind of just live with the results from there and trust our teammates to help us on the backside. So I think we just got to stop letting them get comfortable in the beginning.”

In addition to Bridges’ 3-pointers, the Heat also were victimized by Jalen Brunson’s 6 of 13 from beyond the arc in his 47-point performance, the highest-scoring game against the Heat this season.

“It’s got to be more,” coach Erik Spoelstra said of his team’s 3-point defense. “It could be something different. (Sunday), they hit shots while we were there. Other than Bridges in the first half, I thought he shook free for some transition threes. Brunson’s threes, we’re there. If they’re making them, what it requires is more.

“You don’t know what it requires until you get the stop, and we’re going to get there.”