My digital kitchen scale turns off pretty quickly after use. This is terrible, because it also doesn't remember tare (i.e. the weight of the empty container you put onto the scale prior to filling it), so when you turn it back on it zeroes on whatever's on the scale. Did not read the measurement immediately, or forgot the value? You now have to empty the content into another container and try again. Annoying if you're measuring uncooked rice. Infuriating if it's sticky, ultra-viscous fat.
My dishwasher has a "COMPLETE" light that tells the household that a washing cycle finished after the door had last been closed, a signal that the contents of the dishwasher are likely clean (unless you leave the light on after emptying, but we rarely forget). But if you close the door accidentally just once after that, the light stays off, and there is absolutely no way to put it back on without a washing cycle. I read the manual, tried various logical and illogical key combinations, nothing. Now you have to tell your household "I didn't have time yet to put all the clean stuff out but the light is off, please remember that".
My TV likes to switch automatically to its internal speakers for various reasons, which I never want to use because they are terrible in this particular TV, and switching back requires going through multiple laggy submenus. But worse, if I turn the TV on and notice it's on internal speakers again, I have to wait for it to finish booting completely before I'm allowed to navigate the laggy submenus.
To leave this rant on a more positive note, though: The digital interfaces of my coffee maker, my microwave, and my water cooker (multiple temperatures, auto-reheat, auto-shutoff) seem to do exactly what they should, under many and sometimes non-trivial circumstances, so I'm glad good UX design still exists.