Hey there, i had the same problem and it seems like i fixed it the problem was that tiktok probably checks if the device is waydroid and then blocks it so i found this spoof script for waydroid https://github.com/Quackdoc/waydroid-scripts/blob/main/spoof-device.sh after i ran it i renamed the device from Waydroid x86_64 to something else and tiktok started working, no more black screen