wait for mod to confirm but, pretty sure your skills will stop at your new group's cap until they lvl up the limits,

you don't need to respend your points if you bought it before in ur prev group, you just gotta wait for the group limit to lvl up.

I can personally confirm that they'll downgrade to your new group's level cap.

But if your new group levels up (or you join another group with higher cap) you will get your 'lost' stats back.