Modern Vespa

I recently bought a 2010 Vespa LX50 4T 4V with 4200 km on it. It had been sitting unused for five years. After getting it, I thoroughly cleaned the carburetor, air filter, changed the oil, replaced the battery, replaced the old gas with fresh gas and checked the spark plug. The scooter starts, idles, and runs fine, except when I give it full throttle. At full throttle, it begins sputtering and backfiring. However, if I ease off the throttle just a little, about 5%, it runs perfectly and reaches 45 km/h as it should.

I recorded a video of the issue while the Vespa was on the center stand, and it behaves the same way on the stand as it does when I'm riding.

What could be the problem?
https://youtube.com/shorts/UCNfc7LXcVA?feature=share

Not sure if there is a rev limiter in this scoot, but it sure sounds like that.