I don't know if original claim is true or not in general, but lenta.ru in particular is a poor source of information, it's heavily skewed into Russian-government side.
It's a bummer that just about every media outlet in Ukraine is either tightly linked to Russian propaganda, or on the other side its mostly super pro Ukrainian (formerly funded by USAID) outlets with ties to weird libertarian billionaires who want to turn Ukraine into free market paradise. Hardly any middle ground.
Sometimes, reported news are actually true, this is from Ukraine's Education Minister:
https://www-unian-net.translate.goog/society/osoblivo-hlopci...
Just think about it logically, if you are a mother of 16 y.o kid, and USA says you must conscript 18+ y.o to receive any further aid - would you just sit and wait for your child to get drafted on his next birthday?