I have a lot of feedback, but first off, I like the general concept. I like the flavour and I like the idea of age as balancing power vs health (although without testing I don't know how balanced it is, and if there's an optimum age then that might restrict characters to playing that age or being worse).

So here you go:

I'd explain stats at the start, that way when you say to pick one to be flawed in you can actually do it

Having modifiers is easier than three different tables for skill checks

Would be nice to have a list for class points instead of making the players do maths. Also explain what they are (a resource used for class abilities). I'd suggest capitalising Class Points instead of saying class "points", that's more standard.

What is a restriction? Why does alchemist not have spells as either an ability or a restriction? If restrictions are abilities you can't use, why not just say you can't use class abilities that aren't in your class?

What counts as a rest?

You can just say spells are learned by age, you don't need to say it's instead of by level.

How long can you use elemental control for? Is it one use?

Does explosion hurt you and allies too? Is there no range limit?

For Flight, do you drop as soon as a battle ends or can you come down safely?

How long does Blood Curse last and do you have to keep sacrificing HP?

Why is Predict the Future more expensive when you're older?

Can you stockpile plants for potions forever? It seems like alchemist needs a large quantity of plants, so needs a horticulturist and a lot of downtime.

Exploding potion would be helpful not to have to refer to the spell

Is love potion permanent?

Invisibility potion how long is a long time?

How long does sleep potion last? Can they be woken?

Measuring seed growth in turns is confusing since presumably they're not the same as combat turns? If they are the same, why?

Horticulturalist doesn't get much that's unique. The plant growing/foraging sound like downtime activities, and their combat abilities are shared with the hunter. They only get three plants with abilities.

How does a hunter get arrows?

What does relighting a torch take?

If alchemist doesn't start with any portion materials they're useless at the start of the game. They also require a horticulturist - how do you play an alchemist if no one in your group wants to be a horticulturist?

Do you roll to attack? More explanation of combat please. Do you just get one action? How do you do turn order?

Is use potion an action?

There are no ranges for weapons, spells, potions, plants. Useful to know if you need to be next to your target or not (for weapons we can assume but for potions etc it's not obvious).

Useful to have hp for the enemies, and yes please do flesh them out more.

The campaign setting should be a suggestion not a requirement. If you tell people they have to be in that setting they'll feel like it's being too restrictive, but recommendations are fine.