For the last friggin time, it used to be age based for youth and grade based for HS. Girls has always been grade based.

It changed 3 years ago because club/coaches wanted to have kids grouped by grade to make it easier for grade based comparisons, rightly or wrongly.

You may not like it, but that's what it is. NY dads complained to US Lacrosse, and now they are trying to put the horses back in the stable. They might succeed, they might not. Until then, just tell your kid to play and stop embarrassing them with your whining.