Actual Biggest?
Gotta be the fact that society is designed for neurotypical people on almost every level.
Many ( not all ) disabilities that come from autism would simply not exists as disabilities with the right social structuring to accommodate people’s complex need.
But i guess you meant something more personal challenging.
Its gotta be the enshitification of the internet. I once considered the network of free information and knowledge a sort of home, but for a while now greed has corrupted almost every level of it. Social manipulation with (hidden) advertisement is everywhere.
I feel like i am constantly being preyed on for my personal data. Constantly tricked with the promise of something actual useful. It is draining me, its causing me to be overstimulated from things demanding my attention. It makes me no longer able to find information, which the tinfoil hat in me says is probably partly by design.