I wanted to ask if it's legal to stream Beat Saber Custom Songs on Twitch. If someone knows about it, an answer would be very nice.
Do you mean with custom songs created by yourself or normal songs that have a Beat Saber map from the community?
Maps created by the community e.g. With songs by Imagine Dragons or other bands.
Copyright is not exactly mine, but I can remember Libra that streaming is not prohibited with songs in the background. Here you also have noises that also falsify the song. And when the twitch bot just briefly silenced the issue until the song is over during the stream.