Only the screed is broken or worse?

Hello everyone!
My better half and I want to buy a house. Today we found one that we like.
There is one catch. The floor is uneven and the tiles are therefore crooked and partially cracked. The tile trim (the half tiles on the wall next to the floor) has cracks in the silicone joints. There are tiles in every room.
The realtor and other interested parties could not say exactly what it is. I am afraid that it has something to do with the foundations or the ground in general and will be very expensive. But I have not seen any cracks in the basement ceiling or on any walls. Could it just be the screed? In the basement, in one room, there were also longer cracks in the screed. If it is the screed, can it be repaired or does it have to be completely replaced?

The house is from the 1990s, but has been unoccupied for 2 years. The condition is otherwise appropriate for the year and good. Everything looks like expert work and not like a DIY job.

For those who try remote diagnosis here: Thank you very much, Merci, Gracias

That would mean. Removing all tiles and floor coverings, breaking out the screed. New screed, new leveling compound, new coverings and tiles. It is possible, but involves a lot of dirt and many man-hours.

That would mean everything with tiles and floor coverings out, breaking out the screed. New screed, new leveling compound, new coverings and tiles. It is possible, but associated with a lot of dirt and many man-hours.

Hello Nordlys,
thank you for your answer! That is a lot of work, but it would be okay. At least it's plannable. In most rooms we want to throw out the tiles anyway.
Do you think it is only the screed or could it be something worse?

No idea. But cracked foundations are not impossible, although very rare. Earthquake zone? Heavy freight train traffic nearby?

No idea. But cracked foundations are not impossible, though very rare. Earthquake area? Heavy freight traffic nearby?

Rural area in West Hesse. Never heard of earthquakes there. The only trains are carnival trains.

Sounds to me like the screed is "bowed." It was either dried too quickly or covered too early back then. The tiles have to come out, but with a bit of luck, the screed is usable. However, you can only see that once the tiles are removed.

Edit: Chiseling out the screed is a bit of work, but basically easy to do. New screed costs us around €14-17/m² net in the corner.