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

I used to teach high school and have an advanced administrative degree. I highly doubt any school staff would think less of you for this, unless they’re exceptionally shitty people. I hosted some activities where pictures were taken, and if a student had returned later and requested one or more of them be taken down, I would have complied with no questions asked, even if consent had previously been granted by the student/their guardians.

While it’s true that there are some awful teachers and administrators, the vast majority wouldn’t have a problem granting a simple request like this.

I hope so, i really do

People downvoting you clearly don’t know that school administration can be into bullying as much as the kids. Talking by experience. I think you can report the images in Instagram by saying you’re in them and don’t want to be.