Sulfur smell in the attic after plumbing appointment

Hello, after a plumbing appointment took place in an apartment of a multi-family house, there was shortly afterwards a sulfur smell in the apartment above (3rd floor attic) coming from the water pipes. I am trying to find out where the sulfur smell could be coming from.

On the 2nd floor: The drains of the washbasin and kitchen were cleaned today and a pipe ventilator was installed at the sink so that the water arrives at the tap with the same pressure without sputtering. In addition, radiators were bled and the pressure of the central heating was increased. Can someone help me?

The smell when bleeding the radiator that I know could certainly be described as "sulfurous."

Have you already asked the plumber? That would be the easiest.