As we near session zero day my group is asking questions about ancestries. My question to you is regarding rare Ancestries. Not info about the ancestries themselves, but rather the (rare) tag.
I found this info (PC2) about uncommon ancestries and heritages, and rare backgrounds.

But does something like this exist for a rare ancestry? I was hoping the Ancestry Guide would have something.
Thank you this really helps a lot. I have a player wanting to play a sprite. I am thinking of limiting his flight to small bursts, because I can see already how it will be game breaking at times.
Sprites have to burn an ancestry feat to gain a 15 foot fly speed. It's a significant boost to their flexibility, and gives them the ability to both reach enemies who might be in places where the party wouldn't otherwise be able to touch, but they have to end their turn on the ground, so it's not like they can really avoid the worst of combat.
I wouldn't stress about it too much. There's utility there, but if it becomes a problem, it can be planned around.