In terms of UQs, Pettas and Nex alternate. However we don't know how that's going to look when mining defense gets added next week but it would be safe to assume that the three would rotate. (Also worth mentioning as above that both Daityl and Nex have gigantix variants exist as well.) As a side-effect though, this means that Pettas Vera will be happening less frequently and is going to cause more issues with obtaining Pettas Soul capsules reliably.
Also Pettas Vera does not have a UQ equivalent outside of regular Pettas and Pettax mobs, unlike Nex Vera. (who of course has Nex Aelio) I have noticed more recently that pettax mobs have been dropping Pettas Soul capsules a little more but is still very, very low so I don't think it's balanced out. It does help that both Pettas Vera and Nex Vera now drop two capsules per UQ right now. (Not sure if that's just for the event or something else.) Either way a fair balance for Pettas Soul capsules compared to Daityl and Nex Soul capsules is still to be desired, and the addition of Mining Defense into the UQ rotation is probably going to make it worse.