I still have my $120 fridge from like 2010-2011ish back when Sears was a thing and it's still going without any issues. Zero maintenance ever needed thus far.
No ice maker in it, and the freezer part is on top like in the pic. Apparently if the freezer is on the side instead of on top, those break down way more often.
I have a freezer on the top too. It did collect some ants for whatever reason (my house is a literal ant colony at this point) but it still works OK, just like the bottom part (where it says OK).
It's not really a temperature sensor, it always says that regardless of how cold you set the fridge (and no, absolute zero is not possible, sorry for ruining the fun).
But, depending on how cold the fridge is, it turns blue, but the bit that says OK stays white.