Interference
Interference is unwanted signal or electrical noise that disturbs reception. On DAB+ it shows up as dropouts or silence, not hiss.
Interference is anything that disturbs the radio signal on its way to the antenna or inside the radio. Sources include electrical devices, faulty power supplies and some lamps.
dabplus.ch names LED lamps and other interfering electronics as a possible cause of poor DAB+ reception. A simple test is to switch the suspect device off for a minute and run a new station scan.
The symptom differs from FM. FM becomes noisy and crackles. DAB+ goes silent at a weak signal instead, as Kassensturz noted in 2019. A radio that works in one room and not in another is a typical sign.