The only thing is that they only show 30 CUs (Computing Units) instead of 60 CUs.
The RX 580s display 36 CUs.
Maybe some scholar knows why ...
It may be because RDNA and RDNA2 both have Dual CUs so Phoenix miner kernel look at it as 30 instead of 60. Maybe in some update they could make it display the AMD conventional count of CUs on RDNA cards.