Councils have some ability to set matters for approval, but it’s done via a permitted development right, which is (in effect) a national grant of planning permission, so they’re minor technical matters rather than the bigger questions around suitability of use.
The law has been changed a bunch of times, there are now requirements for natural light and soon (or maybe already, dunno when it actually comes in) they’ll have to meet a national minimum space standard (which is pretty decent iirc). That’ll mean new stuff like this can’t happen, but isn’t backdated or anything.
They’re all subject to building regs checks I believe. I don’t know much about that really, although it’s very much technical safety issues and again doesn’t cover suitability of use.