Techniker, sadly it is because after 24 you can not be part of the family insurance anymore.
no if you earn less than X euros / month you don't pay taxes, as it counts as a minijob. many students do these minijobs. the amount used to be 450 euros but they raised it to 520 recently due to the inflation.
now, i have worked already for 4 years as a codemonkey full time because at age 18 i was not mature enough for uni and i quite after a year. until age 24 you can be part of your family health insurance and you don't have to pay extra but once you turn 24 they ask you for 200 euros / month if you are still a student, even if you have no income at all.
i can quickly make the 520 bucks while my younger uni mates have to do shit jobs with minimum wage for a much longer time but this advantage is basically worthless because the health insurance now wants my money because i'm too old.