It's really not much different than most cars people use every day. Nothing weird is happening with my seats. (Sealion 7) And I put 40kg+ in the boot without problems either. I've not seen reports of this being a problem overall - maybe you just got very unlucky?

I get not liking something for personal preference reasons, but going as far as garbage and cheap quality in this case just... doesn't match reality. It's a perfectly fine car that works. Lots of people are happy with it.