It might be apparent by now that I get bothered by silly or strange things. But what’s the point of even having a pet peeve if you can’t enjoy it?
Thermally stratified tanks bother me. Fill a tank partially full of cryogenic liquid, leave it alone for a few hours … maybe even days. Even with great insulation, you’ll have a heat leak into the tank. The liquid will boil at the wall perhaps, and may also vaporize at the surface. The pressure will build slowly.