Don’t call it a Hollywood fling!

The relationship between “Euphoria” star Sydney Sweeney and music mogul Scooter Braun is “full throttle,” a source tells Page Six.

“They are full on,” the insider tells us. “It’s not a casual relationship. It’s game on, it’s full throttle. They are together.”

The 28-year-old actress and the 44-year-old music powerhouse — who was behind the starts of Justin Bieber and Ariana Grande’s careers — were spotted holding hands on a double date with her parents at Universal Studios Hollywood in Los Angeles on Sunday.

The day before, he attended her space-themed birthday party. And last week, they were seen on a dinner date at trendy Jon and Vinny’s in Brentwood, Calif.

Despite the age gap, our source tells us this isn’t a fleeting flirtation.

“He is pick

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