RU-vid used to have a tool that let you look up songs and see if the copyright holders would allow other people to upload their stuff or not. Pretty sure they got rid of that tool though. If you ever wanna get back into reactions, one thing you can do is download whatever video you're about to react to, then upload that same video to your channel as "unlisted" or "private" and see if it gets blocked. If it does, then you know not to waste your time doing a reaction to it. Still gonna be wasting some of your time, but maybe not as much as before.
