Is it safe to buy a house with cracks in the masonry wall?

I chose a house to purchase, new construction. The walls are made of expanded clay blocks, ecowool, facing brick. Foundation strip + piles, strip depth of 2 m. Reinforced tape across the tape 12 armatures in the corners of 8 reinforcements, piles also reinforced.

Soil is clayey, but the neighborhood itself is on high ground, groundwater is deep (as we were told).

The house was standing without heating, as soon as it was turned on, almost immediately went a crack from the largest window, where the stairs, and outside (up from the window and just below it), and inside the house (only up). The builder said the problem was that the heating was turned up to its maximum at once.

There is a crack on the outside on the brick under the window on the other side. There are cracks on the foundation all around where the vents are, there are plastic pipes. The crack beacons have not been put in yet, will be put in this week.

Can you please tell me what these cracks are, how dangerous they are? And how can we make sure there is no problem with the foundation?