what logical fallacy does this use

One time, I saw a student place their plastic water bottle in the trash can instead of the recycling bin, and this clearly means that we have a recycling problem at our school

The logical fallacy used in this statement is "hasty generalization." The conclusion about the existence of a recycling problem is being drawn from one specific incident (seeing a student place their plastic water bottle in the trash). It is not justified to make a broad generalization about the entire school's recycling practices based on this single observation.