FM Reception suddenly poor?

I parked the car up for a week due to illness, when I got back in the FM reception seems to have become suddenly really bad, it's fine in some places but on what seems like the same points on my commute is terrible.

It's always been fine, so I can't figure out what has happened... does anyone have any ideas what I can look for?

I have, but I always did - and it's strange because in places it is fine, but in places it used to be fine its now awful but across multiple stations.

I remembered that 'd bought a new car charger for my dashcam, this is the culprit I've replaced it, but the new one still kicks out a little bit of interference, although less.

I'd bought the original one because it had a hard on/off switch so I didn't need to keep plugging/unplugging - the new one also has an on/off switch but a permanently powered LED as the cigarette socket is always on..

Seems like whatever I buy ahs a compromise, I'm ideally wanting something that draws no current when the car is off...