Why does my gaiwan always seem to bring out the astringency in high-end Keemun teas?

I've been experimenting with different brewing methods and equipment, but I've noticed that whenever I use my trusty Yixing gaiwan, the astringency in my Keemun teas becomes almost overwhelming. I've tried adjusting the water temperature, steeping time, and even the amount of tea leaves, but nothing seems to mitigate this issue. I've heard that gaiwans can accentuate the nuances of certain teas, but I'm starting to think that it's actually bringing out the worst in my Keemun. Has anyone else experienced this problem? I'm using a fairly standard gaiwan from a reputable manufacturer, and I've had it for a while now, so I don't think it's a matter of the material or craftsmanship. Maybe it's just a matter of finding the right tea to pair with this particular gaiwan? I've got a few different Keemun varieties in my collection, but so far, none of them seem to be able to balance out the astringency.