Digital Radio - why to avoid Chinese dashcams 

The common problem caused by non-compliant CE (aledgedly tested - think not) Chinese dashcams.
If you want your DAB Digital Radio to work you are best avoiding the cheap Chinese dashcams as they will interfere. There is also a very common brand in the UK that has the same issue (next....).
Basically the electronic interference generated by the dashcam wipes out DAB reception. You can try decoupling the power supply and adding ferrites, but will not cure a badly designed product.