Okay, off the top of my head, without googling:

• Testimonies from people who escaped
• Satellite evidence of large labor camps
• Satellite evidence of villages becoming depopulated
• Testimonies from former workers in the camps
• Video of chained-up people being marched into camps
• That guy who said he bought "halal organs" from China
• That time at the UN when they accused China of attacking Uyghurs, and the CCP guy got all pissy and defensive, but didn't deny it

people would want to share the evidence

Almost as if there's an enormous state surveillance apparatus that will black-bag you if you talk? Let's not pretend China has freedom of speech here.

And I'm sure you could pick apart the claims and the sources, and find biases, and say we should give the CCP the benefit of the doubt, but there's really no reason to do so--what evidence is there that the CCP have changed their ways for the better?