AFAICT, Harley's XG750 has always struggled, and continues to struggle.
It's not even sold anymore, and what is running under the Vance&Hines banner is highly massaged.
Currently, HD riders are in fourth and tenth AFT rankings.
There's a lone KTM out there, and the rest of the top-tier are on Indian.
My bare understanding of the deal is that there was a schism of thought back in the early '20-teens' when the series organizers said they were switching to a production-based series, so HD got in line with that thought.
But Indian rolled out a pure-racing motorcycle, and then the series never changed.
https://www.cycleworld.com/is-indian-ftr750-really-that-good-is-harley-davidson-xg750r-really-that-bad/https://www.americanflattrack.com/assets/view/28694/2025-AFT-SuperTwins-Redline-Technical-Rules-2024-08-16.pdf
Choose to Ride.
Supports splitting everywhere.