Why should you withhold giving parenteral iron when there is an active infection?

In the UK, it is estimated that 3% of men and 8% of women have iron deficiency anaemia. Would giving parenteral iron add any clinical benefits to the patients now? What is the expected onset of action on the haemoglobin and iron levels? doi:10.1001/jamanetworkopen.2021.33935 doi: 10.1016/j.bbagen.2008.07.002