As long as it's 95C or below SUSTAINED, it is fine. Spikes do not count.
GDDR6X has high operating temperatures, but uses very little power - literally in the single digits of watts.
As you're already aware, RTX 30 has some of the highest power draw to date. Those memory chips are soaking in some of the heat radiating from that.
There's also the matter of how some card's coolers are built. Some don't seem to have put as much thought into memory cooling as others, such as backplates trapping heat instead of helping to move it away. :/
1)There's changing thermal pads, which I believe some people are too quick to fall towards as a solution. Plus, it can be a matter of trial and error if it's a model no one has successfully reported replacing the pads for online.
2)The biggest issue is the memory chips soaking in a heat bath, right? Then just cut back on the power draw. Lower the power limit to a point that just about matches Gpu Boost at the default power limit. Experiment to find that happy medium.
3)People like seeing big numbers right? But that also means more power being drawn... yep, that's right: use fps caps(if the game doesn't already have limits built in).
TL;DR: Cut back on the power draw and use fps caps. It'll reduce the amount of heat radiating from the PCB, meaning the memory chips don't soak in as much.