TikTok and YouTube Live Gaming Problem

This problem is about live gaming streaming on TikTok using Samsung DeX. Before this, I was using a Samsung S20 Ultra with the older DeX version. When I did live gaming streams, the floating mini windows for chat and settings from TikTok and YouTube showed up on the monitor, and the internal game audio was captured in the live stream.
Now I’m using a Samsung S25 Ultra with the newer Samsung DeX. But when I stream games, the floating windows don’t appear on the monitor anymore. They only show on the phone screen, and the size is very small. On top of that, the internal audio is not captured in the live stream—only my microphone voice is recorded.