Developer warranty for third-party services

Thank you again for the helpful answers.

As a layperson, I would however like to reconfirm my understanding...

The starting point is that two bathrooms will be tiled, the rest was intended for parquet. The vinyl height will be lower than the parquet, meaning a height adjustment must be made.
Question: Until now, I thought this adjustment was done by the vinyl flooring installer by filling – or is it done by the builder, and if so, how?

The problem could be that the doors are not quite right or cannot be adjusted without the floor being installed and therefore may need to be shortened once the vinyl is laid.
Question: Is this a problem or do I need to give the builder instructions (e.g. to adjust all doors to the height of the tiles, since in the rest of the area the vinyl floor is to be adapted to the tile height)?

Question: So far I thought this was done by the vinyl floor installer by filling - or is it actually the developer, and if so, how?

On the one hand, ask your supplier and on the other hand the craftsman for the floor coverings what each prefers. Both ways are generally possible, but not for every height difference.

Question: Is this a problem or do I have to give the developer specifications (e.g. adjust all doors to the height of the tiles, since in the rest of the area the vinyl floor is supposed to be adapted to the tile height)?

It will _only_ become a problem - for you - if you do not take care of it in time Rheinische greetings

As already wrote, discuss the floors early with the builder. The screed layer can ensure that the screed is adjusted in advance to the floors to be laid. Due to the tolerances (I don’t know exactly how many mm), I would have vinyl laid first, then the tiles. The advantage is that the tolerances can be better compensated with tile adhesive than with vinyl. Only once the floors are laid, have the doors installed. This in turn saves time for the floor layers, because they neither have to shorten the frames nor cut around them. The carpenter also saves time when setting the frames because he no longer has to consider the height of the floors. Furthermore, no soiled frames and nice, even joints between floors and frames and between floor and door leaf.
Regards, Sigi

We directly specified our floor height to the interior door installer by placing a cut-to-size piece of the floor covering, including impact sound insulation, directly against the door... thus physically providing the finished height as a sample. With this sample, he could determine the necessary height at each door. The installer is grateful that he can see the correct height directly, and you are grateful that the chance of errors has been significantly minimized. This approach was positively received by our construction company because they often have to guess how high the floor might be. And that is just stress that could be avoided (and one would always have to live with the defects since replacement would not be reasonable...)