Building a house in winter: Water in the basement - Fear of mold

Hello everyone,

We have been building a solid house since mid-September.
So far, the basement (white tank), ground floor, and upper floor (ceiling is on) are in shell construction.
The ceiling has now been covered with a foil - there are no windows installed yet.

During the construction of the house, it snowed heavily from time to time. The melted snow ran through the stairwell into the basement.
I would say that about 3 cm of water is standing in the entire basement - for 1.5 months.

The construction company said this is normal and will be pumped out in the end.
However, the interior walls of the basement are built with masonry and not concrete.

After reading on the internet, I am now really a bit panicked that due to the high moisture we already have mold in the basement or that it is already taking hold in the masonry.

Therefore, I have three questions and hope for your experiences.

Is it really normal to leave the water standing in the basement for so long -> I will pump it out myself tomorrow.
Should the windows be taped up, because naturally moisture also gets into all the other floors, or would that prevent air circulation?
Does the attached picture show mold on the masonry?

I am really very worried that we are already too late and that the mold endangers both our health and our masonry.

I would be very happy to receive your feedback!

Best regards!

So the water has been rising up through the masonry of the interior walls for 3 months?

So the water has been rising up in the masonry of the interior walls for 3 months?

I would say for about 1.5-2 months

So the water has been rising up the masonry of the interior walls for 3 months?

I just checked again. There has been water in the basement for about 1-1.5 months.