Which flooring goes over tiles?

My brother-in-law had a specialist company apply leveling compound (especially for the joints) on tiles that are about 20 years old years ago, and then installed design flooring made of 2mm vinyl. Fully glued down, naturally. And that in a very large open living kitchen area extending into a small conservatory. I think it cost about €70 per m2? The build-up height was only about 3-5mm? Here too, the removal of the tiles would have been problematic due to the existing underfloor heating. It turned out well, and after minor adjustments (especially in the sunny conservatory) everything was fine.

we actually considered liquid floor, microcement or filling in concrete / industrial look.

That is expensive and not necessarily as durable as one would expect from concrete. We have it in the office and when the glass walls were cleaned for the first time, the cleaning water left stains everywhere. But it’s not just due to the cleaning agent; if someone drips watering water for the plants, you can see that too. And even more so in the coffee kitchen. After a mere 3.5 years, the landlord finally decided to have it sealed. That was 3 weeks ago and it still smells. I wouldn’t want that in the living area.