Why did our 7 month old puppy stop wanting to be in the sleeping kennel literally overnight?

First of all, we’re not really complaining- we would have liked for him to stay in the kennel until he’s 1, but he’s not tearing the house up at night or anything.

We got our German shepherd cross puppy in early May, and he’s been a DREAM at kenneling overnight. We don’t kennel during the day because he has his own bedroom with a baby gate, so he’s free range in there instead. But at night he always took his peanut butter treat and went to bed peacefully in his kennel, which is in the room across the hall from ours, and is covered. He happily slept all night, and he even peacefully kennelled at the dog sitters when we were away a bit in June.

As the title says though, we had a completely normal weekend, standard bedtime routine, he walked into his kennel as usual on Saturday night, and proceeded to lose his mind once we turned off the lights and went to bed. Whining, barking, eventually physically thrashing around his kennel. We took him out for potty, gave him his usual treat again, put him back in, and he lost his mind yet again for 30+ minutes. His favorite music didn’t help, verbally reassuring him didn’t help, potty breaks didn’t help, more comfort items didn’t help- nothing worked. We finally gave up at 3am as none of us had slept a single minute, and he peacefully slept on our bedroom floor the rest of the night.

Same thing happened last night.

This has NEVER happened before, he’s never so much as barked in his kennel before Saturday night. Why did he lose his mind about his kennel literally overnight?