CNN is reporting some in the intelligence community aren't sure she was but there's skepticism that's just planted spin from the Trump admin.
But one theory being discussed is she was running a smuggling ring to get chips from Nvidia for her own reasons and China figured out she was hooked up with Huang and then decided to recruit her and whether she signed on or not it was that Chinese recruitment of her that set off the bells and whistles with US intelligence.
The reason some think it's just Trump admin spin is that Singapore had already decided she was a spy, they held her at one point and even after releasing her they were holding her passport for awhile.