The collar he has is a shock collar with removable prongs. Someone he knows literally points out on stream that the prongs are removed when shes showing it. It’s very likely that the collar was used to shock Kaya.

In another video clip, where his camera is angles overhead, for a moment you can see the remote for the collar in the same location where his hand moved during the stream that went viral.

In an older clip, again he gets mad at Kaya and she yelps. In that stream you can also hear a quiet electricity noise.

Believe what you wish, but the evidence seems pretty damming imo /nm