Get that interview process fixed ASAP and let this lemon go. Don’t be surprised if there is pushback from non-technicals if this hire checked a bunch of boxes for other departments. A good strategy would be to have them be a lead on a minor project that requires technical chops and communication. Ensure there is a daily standup and grind them on details and timelines. Get them some juniors as direct reports to expose…
This proto-sociopathic behavior is the direct result of European employment law. It's disgusting.
If someone's under-performing whilst in their probation period getting rid of them is incredibly easy. Outside of the probation period there's a bit more of a process, but it's still not particularly hard - all you actually need to be doing is documenting.