I bought IKEA king size fitted flowery sheets for a double bed.
Because they are dark background I’m always clean, wear pyjamas and slippers etc., I washed them on 40deg, as opposed to 60deg. hung them on the washing line.
They still shrank. One side fits perfectly, the other curves upwards. They are meant to be deep but not any more.
I now fit two identical sheets one on top of the other which camouflages this effect.
I have considered flat large cotton sheets, an alternative as
elasticated corners take a while to dry, then the struggle to haul them into place as described, these fitted sheets which I believed would make bed making easier.