Issues on reflecting proc or skill

[arcanefid]

Assuming you mean reflection from a 71 item, if you're in a 71 group, it should do full damage in those zones, since they'll be 71 zones (with mobs scaled higher). If you're in a higher level group, those zones scale higher, so your reflection from 71 items will be reduced.

This is true for PvP too?

[Futumsh]

This is true for PvP too?

Yes, a 71 item providing damage reflection is less effective when the person it's being reflected on is over 71.