[2023] Update made the game unplayable

The issues you describe only affect worlds from Update 9.7. Migration to 10 only ensures loadability - the versions are too incompatible for anything more as tons of things changed (which is also the reason why your machines now work differently, that is not broken but intended changes). We recommend to start a new save for new major versions in general.

You can turn on building on deep ocean in Difficulty.eco file:
"AllowDeepOceanBuilding": false,

Set it to true.

We did keep them loadable as we had quite a bit of feedback by players in the past that would like to just visit older saves to take a look on what they built for "historic" reasons. I'm honestly not sure that was a good idea, but we're also humans with learning processes :)

We will address issues that are not caused by the migration (there is some related to settlements off), but none that are caused by the migration itself, given it's just not possible.