ᐅ Professional Installation of the Bathtub in New Construction

Hello,
can someone assess whether this bathtub, installed by a plumbing specialist on behalf of the construction company, has been fitted correctly? I find it surprising that they used different and broken bricks, especially since there was still a pallet of new sand-lime bricks right outside the house, from which they could have taken four pieces. Is this thin rubber layer sufficient to ensure sound insulation?

Unfortunately, the construction company also made an arbitrary cutout in the screed; on the short side, the screed extends under the bathtub, while on the long side it is too short. They are now trying to shift this responsibility to the tiler.

If the bricks are cast into the screed to fix them in place, should this be left as is, or does something have to be corrected? Behind the still-to-be-installed tiling, would you insulate the cavity yourself with mineral wool, or leave the void because it supposedly makes no difference?

Thank you very much!

Everything looks fine to me. You won’t see any of this later, and nothing will collapse or break down. How far the screed extends doesn’t make a difference either.
If you want to maximize sound insulation, then attach Hawaphon to the underside of the tub and fill the cavity with a suitable material like mineral wool. Avoid anything that could potentially develop mold.

Fits perfectly. Nothing visible later on!

What would confuse me more is why an electrical cable was installed directly underneath the bathtub....