I mean it is possible that the 6nm process is fantastic for higher clocks.. but your original theory does not fit the 6500 XT, it's trash.Well, it has just 4Gb of VRAM, quite a drawback, but not really if playing at 1080p resolution.
I'm not really making an argument in favour of the RX 6500 XT, just pointing out that 6nm appears to be quite a positive development if it allows improved clock rates on RDNA2 refreshes.
If you limit the card to reasonable usage it's a better product, but you have to limit it so that it don't fail at what other 4GB cards with a wide - bus can already do.