School shooters don't fit a single profile. Some of them are well liked and popular like Jaylen Fryberg and the perpetrators of Columbine were bullies themselves rather than being victims of school bullying.
I've found that Brave is the best web browser for my old Android 4.4.2 smartphone. Firefox is far too slow, Chrome is fast but it doesn't block ads, and those fake VPN ad blocking apps make my phone get hot, drain the battery, and adds an additional troubleshooting step if my internet stops working.
I use Brave browser plus adguard dns. They support dnscrypt and I've got it enabled on my OpenWrt router. Adguard does break the internet a little bit because they block those tracking links that quickly redirect you to the website that you wanted to go to. I think that the Pi-hole is a better option if you need or want to do any personalized customization to your block list.
If YouTube is willing to please their advertisers or decrease liability by banning content on hacking which could help people within the computer industry identify and prevent cyber attacks, then I wouldn't be surprised if YouTube banned everything related to drug harm reduction and educational content about how they work inside the human body for similar reasons.