Tell your school you don’t want your picture to be online (on Instagram) and ask them to remove it.

If i do that i’ll probably be targeted by the school staff and the people in that photo as an idiot that is scared to show his faces on photos, and if i explain that it’s a matter of privacy then i’d probably look weirder

If they don’t agree to take it down tell them you don’t consent to it or something and you’ll get more involved in taking it down. Letting them know because of privacy will make it become more normalized. If more of your friends who were posted without their consent spoke up about it, this could be a serious issue and maybe they’ll even use pixelfed one day. It’s a long shot but little things like this will bring awareness to people.

For example, over the past few years I’ve been just living my life on a linux computer, grapheneos phone, using foss and encrypted messengers. My friends and family questioned it and I explained to them and a couple them now wanted to get started on this privacy journey. They’ll probably get their family and friends to take notice and explain it to them too, then, it’s a whole movement now.