Can they refuse after the interview because they wanted too much salary?

Question

Career in IT

That is, send a standard refusal without indicating the reason:

Unfortunately, at the moment we are not ready to make you an offer.

Or if everything suits them except for the desired salary, then they will probably write about it?

Answer 1

Могут вообще без причины отказать, закон не запрещает.

Answer 2

a combination of factors,
sometimes a person is not needed urgently - they are slowly looking for a suitable one for the project,
and sometimes the outgoing person changed his mind, etc.