ORCHARD PARK — There were a number of reasons the Jets lost to the Bills, 20-12, on Sunday at Highmark Stadium.

But there were two plays that stood out as the biggest reasons — an ill-timed encroachment penalty on linebacker C.J. Mosley on a Bills fourth down that kept a scoring drive alive late in the first half and a fumble by running back Michael Carter late in the game.

The Mosley penalty came on a Buffalo fourth-and-1 from its own 39-yard line just inside the two-minute warning in a scoreless game.

With Buffalo tight end Dawson Knox looking like he was going to take a direct snap, Mosley dove over the line and blasted Knox — before the snap. He was called for encroachment and, four plays later, the Bills made the Jets pay for the Mosley gaffe.

Bills quarterback Josh Allen connected with Knox on a 24-yard scoring pass for a 7-0 Buffalo lead with 26 seconds remaining in the first half.

“Good pre-snap play design,’’ Jets head coach Robert Saleh said, crediting the Bills. “They probably weren’t even going to snap it. That’s kind of the in-vogue thing now where the quarterback looks like he doesn’t know what’s going on and they snap the ball with somebody going in motion. Miami got us on one [earlier in the season].’’

This one was costly, though.

“There was a chance they were going to snap it,’’ Mosley said. “This year, a lot of teams are doing that. Instead of using the quarterback sneak they’ll let somebody motion — a running back, receiver or tight end — come in and snap it quick. We’ve been beat on that like three times this year, so I just took a shot and unfortunately it didn’t work out for me.

“If I’d have made the play, it would have been great,’’ Mosley went on. “Unfortunately, I didn’t.’’

Mosley’s teammates weren’t critical of the play.

“He was just shooting his shot,’’ edge rushed Carl Lawson said. “Sometimes, it’s like damned if you do, damned if you don’t. Sometimes, you’ve just got to take your shot.’’

Carter’s fumble with 5:34 remaining in the game moments after a Jermaine Johnson blocked punt had cut the Buffalo lead to 20-9 was a killer.

The Jets had wrested momentum from the Bills and were nearing the red zone when Bills safety Damar Hamlin punched the ball out of Carter’s arms while Carter was straining for extra yards. The ball was recovered by linebacker Matt Milano at the Buffalo 20-yard line.

Carter, one of the most respected players in the locker room, was so distraught afterward that he initially declined an interview request by The Post, but a short time later made himself available.

“Just trying to make a play, understanding where we were in the game, we kind of needed a touchdown,’’ Carter said. “I just tried to score a touchdown. I tried to run [Hamlin] over, tried to crank him up. And then he made a good play. Credit to him.

“I had a tough moment there. Overall, I was having a tough game [5 yards on five carries] and I wanted to be there for my guys. I wanted nothing more than to be able to help the guys win. You’ve got to win the turnover battle to win the game. The guys know I love this s–t. I want to apologize to them. They got my back, so it’s understood.’’

Receiver Braxton Berrios called the fumble “a tough break.’’

“You try not to let that happen, but Mike Carter has been a baller for us,’’ Berrios said. “He’ll learn from that and we’ll learn from that. I’m sure he’s kicking himself, and we’re here to support him.’